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Biomedical subjects

C M Liu

Publications and source records attributed to C M Liu.

At least 91 records · Page 5Linked to original sources
PubMed1990

Quantification of jet flow by momentum analysis. An in vitro color Doppler flow study.

Previous investigations have shown that the size of a regurgitant jet as assessed by color Doppler flow mapping is independently affected by the flow rate and velocity (or driving pressure) of the jet. Fluid dynamics theory predicts that jet momentum (given by the orifice flow rate multiplied by velocity) should best predict the appearance of the jet in the receiving chamber and also that this momentum should remain constant throughout the jet. To test this hypothesis, we measured jet area versus driving pressure, flow rate, velocity, orifice area, and momentum and showed that momentum is the optimal jet parameter: jet area = 1.25 (momentum).28, r = 0.989, p less than 0.0001. However, the very curvilinear nature of this function indicated that chamber constraint strongly affected jet area, which limited the ability to predict jet momentum from observed jet area. To circumvent this limitation, we analyzed the velocities per se within the Doppler flow map. For jets formed by 1-81-mm Hg driving pressure through 0.005-0.5-cm2 orifices, the velocity distribution confirmed the fluid dynamic prediction: Gaussian (bell-shaped) profiles across the jet at each level with the centerline velocity decaying inversely with distance from the orifice. Furthermore, momentum was calculated directly from the flow maps, which was relatively constant within the jet and in good agreement with the known jet momentum at the orifice (r = 0.99). Finally, the measured momentum was divided by orifice velocity to yield an accurate estimate of the orifice flow rate (r = 0.99). Momentum was also divided by the square of velocity to yield effective orifice area (r = 0.84). We conclude that momentum is the single jet parameter that best predicts the color area displayed by Doppler flow mapping. Momentum can be measured directly from the velocities within the flow map, and when combined with orifice velocity, momentum provides an accurate estimate of flow rate and orifice area.

Animals↗
PubMed1989

Immune regulation of the L5178Y murine tumor-dormant state: induction of cell- and soluble factor-mediated inhibition of tumor cell growth by tumor necrosis factor and gamma-interferon.

Small concentrations of recombinant murine tumor necrosis factor (rMuTNF) synergized with recombinant murine gamma-interferon (rMuIFN-gamma) to inhibit tumor cell growth in peritoneal cell (PC) cultures from tumor-dormant mice. A soluble inhibitor of tumor cell growth was produced in the rMuTNF-treated PC cultures, but there was no synergistic enhancement of production of this inhibitor by the addition of rMuIFN-gamma. Treatment of both plastic-adherent PC and nonadherent PC cultures which contained L5178Y cells with rMuTNF + rMuIFN-gamma resulted in inhibition of tumor cell growth. However, in the absence of L5178Y cells, rMuTNF + rMuIFN-gamma induced antitumor cytotoxic activity in the plastic-adherent but not in the plastic nonadherent PC. These results indicate that the antitumor activity of rMuTNF + rMuIFN-gamma in PC from tumor-dormant mice involves both cell- and soluble factor-mediated mechanisms.

Animals↗
PubMed1989

Purification and N-terminal partial sequence of anti-epilepsy peptide from venom of the scorpion Buthus martensii Karsch.

An anti-epilepsy peptide (AEP) was isolated and purified from venom of the scorpion Buthus martensii Karsch. The purification procedure included CM-Sephadex C-50 chromatography, gel filtration on Sephadex G-50 and DEAE-Sephadex A-50 chromatography. Its homogeneity was demonstrated by pH 4.3 polyacrylamide-disc-gel electrophoresis, focusing electrophoresis and SDS/polyacrylamide-disc-gel electrophoresis. The Mr of this peptide, calculated from measurements in SDS/15%-polyacrylamide-disc-gel and SDS/20%-polyacrylamide-disc-gel electrophoresis, is 8300. The isoelectric point is 8.52 by pH 8-9.5-range isoelectric focusing. No haemorrhagic or toxic activities were found. No toxicity was found even after the dose reached 28 mg/kg. The pharmacological tests showed that the AEP had no effect on heart rate, blood pressure or electrocardiogram, but strongly inhibited epilepsy induced by coriaria lactone and cephaloridine. The fluorescence spectrum showed that the peptide has a strong emission peak at 337 nm. Amino acid analysis suggested that the AEP is composed of 66 residues from 18 amino acids and has an Mr of 8290. The sequence of the first 50 N-terminal residues is as follows: Asp-Gly-Tyr-Ile-Arg-Gly-Ser-Asp-Asn-Cys-Lys-Val-Ser-Cys-Leu-Leu-Gly-Asn- Glu-Gly - Cys-Asn-Lys-Glu-Cys-Arg-Ala-Tyr-Gly-Ala-Ser-Tyr-Gly-Tyr-Cys-Trp-Thr-Val- Lys-Leu - Ala-Gln-Asp-Cys-Glu-Gly-Leu-Pro-Asp-Thr-.

Amino Acid Sequence↗
PubMed1989

DNA damage and repair in rodent and human cells after exposure to JANUS fission spectrum neutrons: a minor fraction of single-strand breaks as revealed by alkaline elution is refractory to repair.

We have examined the induction and repair of breaks induced in the DNA of Chinese hamster V79 and human P3 epithelial teratocarcinoma cells by JANUS fission-spectrum neutrons (mean energy 0.85 MeV) and 60Co gamma radiation in the biological dose range, using alkaline filter elution methods. Fission-spectrum neutrons induce fewer immediate single-strand breaks (ssb) per gray of absorbed dose than do gamma rays, as measured by alkaline elution methods. Previous survival measurements have indicated incomplete recovery after neutron exposures. The present data demonstrate that whereas most ssb caused by exposure to fission-spectrum neutrons can be rapidly repaired by both cell lines, a small but statistically significant fraction of the ssb induced by exposure to 6 Gy of neutrons is refractory to repair. In contrast, all measurable ssb induced by 3 Gy gamma rays are rapidly repaired.

Animals↗
PubMed1989

Flow cytometric monitoring of human immunodeficiency virus-infected patients. Simultaneous enumeration of five lymphocyte subsets.

The utility of CD4 lymphocytes in monitoring disease progression and prognosis of human immunodeficiency virus (HIV)-infected patients is well established. We have modified a previously described antibody cocktail to provide complete lymphocyte subset analysis on 100-200-microL samples of whole blood. This method optimizes accuracy of CD4 lymphocyte assessments and provides simultaneous assessment of four other lymphocyte subtypes of interest in specimens with absolute lymphocyte counts as low as 300 X 10(6)/L. Lymphocytes are classified as Thelper (CD3+CD4+); Tsuppressor (CD3+CD8+); Tnull (CD3+CD4-CD8-, putative gamma delta T-cell receptor); B (CD19+CD20+); or natural killer (CD3-CD16+CD56+). The method positively discriminates against contamination of lymphocyte scatter gates by monocytes and unlysed erythrocytes and is compatible with a variety of cell preparation procedures. Increased accuracy of CD4 lymphocyte determinations and simultaneous identification of other lymphocyte subsets whose relationship to disease progression is under study make this an efficient and informative method for disease monitoring and evaluation of therapy in HIV-infected patients.

Antibodies, Monoclonal↗
PubMed1989

Study of Chinese periodontal patients at National Taiwan University Hospital. Part I: Basic periodontal information and oral hygiene status.

A cross-sectional study of 288 subjects with complete periodontal documentation was evaluated to determine the clinical status of periodontal disease. The patients were divided into age group intervals of ten years. The conditions of oral hygiene and their association with the clinical status of periodontal disease were compared and analyzed. Chronological features of the disease and its background development among Chinese patients is also explored. Our results indicated that in the mind of Chinese patients the loss of teeth was considered to be a natural fate of aging, and dental and periodontal problems were viewed merely as a symptom of pain, but not as disease entity. Most patients were completely ignorant of both the importance of oral hygiene care and prevention of periodontal diseases. A high incidence of ill-fitted restorations, lack of motivations, and insufficient knowledge on prevention were common in our subjects. In this study, the oral hygiene index (OHI) in females was found to be lower than that of males. The OHI dropped abruptly after 20 years of age in females and after 30 years of age in males. The lowest gingival index (GI) was found in the 31-40 age group in both sexes. During the later periods of life, the OHI again rose, and this increase appeared earlier in females than in males. The GI corresponded to chronological changes in OHI. There was no statistical difference in GI between the corresponding age groups of males and females. The periodontal disease index (PDI) increased progressively with age in both sexes. However, no significant difference was noted between males and females. The progression of the PDI appeared stationary in the 31-40 age group, which corresponded to the period of lowest GI. In conclusion, our Chinese subjects exhibited poor oral hygiene and had an associated high incidence of periodontal disease. Irrespective of sex, OHI showed a positive correlation with GI. However, there was no obvious correlation between OHI and PDI. In contrast, GI was highly correlated to PDI in the 21-30 and 31-40 age groups in the present study. In addition, the paroxysmal nature of clinical periodontal parameters supports the recently held concept that the onset and progression of periodontal disease is intermittent.

Adolescent↗
PubMed1989

[Studies on the antiarrhythmic effects of leaves of Dendropanax chevalieri (Vig.) Merr. et Chun].

Aqueous extract of the leaves of Dendropanax chevalieri (DC), administrated orally, showed prominent protective effect against arrhythmias induced by iv aconitine CaCl2 (120mg/kg) in mice and BaCl2 (4mg/kg) in rats. In anesthetized rabbits, the duration of arrhythmia elicited by ivAdr 75 micrograms/kg was markedly shortened by iv DC 0.4g/kg. It might also obviously delay the onset of arrhythmias and cardiac electricity disappearance evoked by ouabain perfusing consistently into isolated guinea-pig hearts.

Animals↗
PubMed1988

Injurious effect of eosinophil extract on the human nasal mucosa.

Eosinophils are frequently associated with the manifestation of nasal allergy in the nasal mucosa and nasal secretion. The role of eosinophils in hypersensitivity diseases, however, is still obscure, whether it protects or damages tissues and activates mast cells. The effects of two kinds of human eosinophil extract (biological and physical extracts) on human nasal mucosa by applying them in nasal provocation test and cilia beating test, and also in tracheal ring incubation and skin test in the guinea-pig were measured. The results of the study suggest that eosinophil major protein and other protein components may produce damage to the function of human nasal mucosa and tracheal mucosa of the guinea-pig.

Animals↗
PubMed1988

Seasonal variation of nasal surface basophilic cells and eosinophils in Japanese cedar pollinosis.

Nasal pollinosis is caused by pollens of trees and grasses as allergen floating in the air during the seasons of blossom. In Japan, cedar pollinosis is the most prevalent of seasonal allergic rhinitis. We studied the seasonal variation of nasal mucosal basophilic cells (cells with basophilic and metachromatic granules) and eosinophils by nasal scraping of cedar pollinosis patients from June 1986 to May 1987, and found that during the season basophilic cells and eosinophils increased significantly, decreased but still remained for two or three monts after the season, and finally disappeared. The variation of eosinophils was more prominent than basophilic cells. The increase of both cells had close correlation with each other.

Adolescent↗
PubMed1988

The role of leukotriene D4 in allergic rhinitis.

We investigated the clinical significance of leukotriene D4 (LTD4) in nasal symptoms of allergy and compared this with antigen and histamine. Nasal provocations were carried out in patients with allergic rhinitis using serially increasing doses of LTD4, histamine, or antigen. The nasal responses induced were evaluated by counting the number of sneezes, the quantity of nasal secretion, and of nasal airway resistance. When the effects of topical provoking agents were compared at the threshold concentration, LTD4 produced no sneezing--unlike antigen and histamine--increased nasal secretion to a lesser degree than antigen and histamine (P less than .001), and increased nasal airway resistance similar to histamine but less than antigen (P less than .1) and longer than histamine, and similar to antigen in duration. LTD4 was approximately 5,000 times stronger than histamine in threshold concentration for nasal response. In conclusion, LTD4 plays an important role in nasal allergy presumably through long lasting and strong nasal blockage effects.

Antigens↗
PubMed1987

Immune regulation of the L5178Y murine tumor-dormant state. II. Interferon-gamma requires tumor necrosis factor to restrain tumor cell growth in peritoneal cell cultures from tumor-dormant mice.

L5178Y lymphoma cells are restrained from progressive growth in peritoneal cell ("in vitro tumor-regressor" PC) cultures prepared from many DBA/2 mice which harbor the tumor cells in the peritoneal cavity in a tumor-dormant state. Treatment of these PC cultures with 'antibodies to murine interferon-gamma (MuIFN-gamma) and murine tumor necrosis factor (MuTNF) but not with antibody to interleukin 2 (IL-2) receptors eliminated the restraint on tumor cell growth and permitted their progressive proliferation. L5178Y cells were found to be resistant to the direct toxic effects of large concentrations (3,000 U/ml) of MuIFN-gamma and of MuTNF, either alone or in combination. Treatment of PC cultures from tumor-dormant mice, in which tumor cells grew progressively ("in vitro tumor-progressor"), but not PC cultures from normal mice, with exogenous MuIFN-gamma resulted in a marked inhibition of tumor cell growth. The MuIFN-gamma-induced cytotoxic activity was cell-mediated since no soluble tumor-cytotoxic factors could be detected in the cultures. MuIFN-gamma induced cytotoxic activity in plastic-adherent peritoneal cell (AD-PC) cultures, but induced no cytotoxic activity in nonadherent-PC cultures unless small numbers (2%) of AD-PC were present, and inclusion of antibody to MuTNF in these mixed PC cultures blocked the development of cytotoxic activity. Antibody to MuTNF also blocked the development of cytotoxic activity in cultures of MuIFN-gamma-treated whole PC and AD-PC from tumor-dormant mice. These results indicate that MuIFN-gamma and MuTNF are both important in restraining tumor cell growth in PC cultures from tumor-dormant mice, and that MuIFN-gamma requires the presence of MuTNF to induce cytotoxic activity in these cultures.

Animals↗
PubMed1987

[Intracavitary afterloading radiotherapy--preliminary clinical report on 44 patients].

This report describes the 2 year results of the treatment of 44 patients (1 vaginal carcinoma, 3 endometrial carcinoma and 40 cervical carcinoma) by Buchler afterloading equipment. One patient with vaginal carcinoma and two with endometrial carcinoma are live without disease over 2 years. There were 40 patients with cervical carcinoma: 1 stage I, 21 stage II (52.8%) and 18 stage III (45%). The dose-rate of the source is 10-25 cGy/min. A total dose of 41-55 Gy was given at point A in 87.5% of cases. The measurement of the bladder and the rectum were made in all the 40 patients during the treatment. The dose at the bladder was less than 30 Gy and only 10% of patients had a dose of over 30 Gy at the rectum. A dose of 40-45 Gy external irradiation by 8MV X-rays was delivered to the parametrium in each patient. One died of cancer, 2 were lost in follow up and 3 had local recurrence and metastasis. The two year survival rate was 92.5%. Only 4 had mild rectal reactions during the treatment and 2 had mild rectal bleeding after treatment.

Adenocarcinoma↗
PubMed1986

Immune regulation of the L5178Y murine tumor-dormant state. I. In vivo and in vitro effects of prostaglandin E2 and indomethacin on tumor cell growth.

Immunization and intraperitoneal challenge of DBA/2 mice with L5178Y lymphoma cells results in the suppression and maintenance of the L5178Y cells in a tumor-dormant state in the peritoneal cavity for many months. Cell-mediated immune responses involving lymphocytes and macrophages are involved in maintenance of the tumor-dormant state. Macrophages that have increased immunosuppressive activity and that produce increased amounts of PGE2 appear in the peritoneal cavity of tumor-dormant mice before the breakdown of the tumor-dormant state and formation of ascitic tumors. We report here that the tumor-dormant state can be terminated with formation of ascitic tumors by treatment of tumor-dormant mice with PGE2. Treatment with indomethacin results in inhibition of tumor cell growth and elimination of all recoverable tumor cells. Cultures of peritoneal cells (PC) from mice harboring L5178Y cells in a tumor-dormant state were used to analyze the PGE2 and indomethacin effects. Tumor cells did not grow out in the high-cell density PC cultures prepared from many tumor-dormant mice, but addition of PGE2 to these cultures resulted in tumor cell growth. The tumor cell growth that did occur in the PC cultures from some tumor-dormant mice was associated with PGE2 production by the associated host cells, and the addition of indomethacin to these cultures inhibited both PGE2 synthesis and tumor cell growth. Removal of plastic-adherent cells from the PC cultures eliminated the restraint on tumor cell growth. These experiments suggest that L5178Y tumor cells are maintained in a tumor-dormant state by host peritoneal cells, which are under PGE2 regulation.

Animals↗