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Biomedical subjects

T Liu

Publications and source records attributed to T Liu.

At least 307 records · Page 17Linked to original sources
PubMed1997

MHC class I presentation of live and heat-inactivated Sendai virus antigen in T2Kb cells depends on an intracellular compartment with endosomal characteristics.

T2Kb cells, which do not express TAP1/2 peptide transporters or the low molecular weight protein 2/7 (LMP2/7) proteasomal subunits, can still process and present both live and heat-inactivated Sendai virus (SV). As this operation may also reflect the existence of an alternative processing pathway in normal antigen-presenting cells (APC), the authors have characterized it using intracellular inhibitors and anti-Kb monoclonal antibodies (MoAbs). From the results with lipophilic amines (ammonium chloride, methylamine and chloroquine), cytoskeletal inhibitors (cytochalasin B and vinblastine), and an endoprotease inhibitor (phenylmethylsulfonyl fluoride, PMSF), the authors conclude that the processing of SV antigen in T2Kb cells has endosomal characteristics depending on cellular activities such as uptake, vesicular transport and intracellular-vesicular proteolysis. In addition, internalized 'empty' Kb molecules derived from the T2Kb cell surface appeared to be involved in the presentation of SV antigen, as demonstrated by a protocol using a combination of the Golgi inhibitor brefeldin A(BFA) and anti-Kb antibodies. The results thus indicate that T2Kb cells process SV antigen in an endosomal-like compartment which contain recycling 'empty' Kb molecules.

Amines↗
PubMed1997

Correlation of toxicity with treatment parameters for 131I-CC49 radioimmunotherapy in three phase II clinical trials.

Analyses were performed on 40 patients with TAG-72 expressing metastatic cancer who were entered into three phase II clinical trials. The dose selected was the maximum tolerated dose in phase I studies. Patients all had unresectable metastatic colon or prostate cancer and had recovered from prior therapies. Patients in trials #1 and #2 received 75 mCi/m2 131I-CC49 antibody whereas those in trial #3 received a total of 75 mCi/m2 with equal amounts of 131I-CC49 and 131I-COL-1. The three trials have resulted in a reproducible degree of reversible marrow suppression; 72.5% of patients experienced moderate or severe toxicity. Comparisons were made between demographic, clinical and pharmacokinetical variables and the grade of WBC toxicity, platelet toxicity and the sum of the two as total toxicity. Whole body radiation dose had a statistically significant relationship with platelet toxicity (r = 0.38, p = 0.015) and total toxicity (r = 0.34, p = 0.035). The bone marrow radiation dose is significantly related to all toxicity indicators with correlation coefficients with WBC and platelet toxicities of 0.47 (p = 0.002) and 0.34 (p = 0.033), respectively. Plasma half-life had the strongest correlation with WBC toxicity and combined toxicities. Multivariate models were developed to help describe the simultaneous effect of these variables on toxicity. The results show that the MTD dose was safely given to patients who varied in age, disease burden and degree of marrow compromise. This supports the contention that a fixed dose of radiolabeled antibody per body mass or m2 can be given to a diverse group of non-lymphoma patients with a predictable toxicity range.

Adult↗
PubMed1997

Catalytic properties of the cellulose-binding endoglucanase F from Fibrobacter succinogenes S85.

The celF gene from the predominant cellulolytic ruminal bacterium Fibrobacter succinogenes encodes a 118.3-kDa cellulose-binding endoglucanase, endoglucanase F (EGF). This enzyme possesses an N-terminal cellulose-binding domain and a C-terminal catalytic domain. The purified catalytic domain displayed an activity profile typical of an endoglucanase, with high catalytic activity on carboxymethyl cellulose and barley beta-glucan. Immunoblotting of EGF and the formerly characterized endoglucanase 2 (EG2) from F. succinogenes with antibodies prepared against each of the enzymes demonstrated that EGF and EG2 contain cross-reactive epitopes. This data in conjunction with evidence that the proteins are the same size, share a 19-residue internal amino acid sequence, possess similar catalytic properties, and both bind to cellulose allows the conclusion that celF codes for EG2.

Amino Acid Sequence↗
PubMed1997

Derepression of prophage P2 by satellite phage P4: cloning of the P4 epsilon gene and identification of its product.

Escherichia coli phage P4 lacks all of the genetic information necessary for capsid, tail, and lysis functions. P4 is therefore dependent on a helper phage, such as P2, for lytic propagation. During P4 superinfection of a P2 lysogen, the P2 prophage is derepressed by the action of the P4-encoded epsilon gene. We have cloned the epsilon gene and identified the 10-kDa E protein. The epsilon gene product is the only P4 protein required to derepress prophage P2, which leads to in situ P2 DNA replication. A two-plasmid derepression assay system has been developed to examine the derepression activity of E. The reporter plasmid contains the two face-to-face promoters, Pe and Pc, involved in the lysis-lysogeny transcriptional switch of phage P2 and the immunity repressor C. The Pe promoter is coupled to a cat reporter gene. In the construct, the C repressor is transcribed from the Pc promoter and represses the Pe promoter, which mimics the in situ-repressed P2 prophage. The E protein is supplied in trans from a compatible plasmid in which the epsilon gene is under the control of the T7 promoter. We show here that in the two-plasmid assay system, induction of the E protein derepresses the Pe promoter. The ash9 mutation, which is located upstream of the epsilon gene, enhances the E-mediated derepression of the Pe promoter. The purified E protein shows no specific DNA binding activity, and the implications of this are discussed.

Bacteriophage P2↗
PubMed1997

Patients' awareness of stroke signs, symptoms, and risk factors.

BACKGROUND AND PURPOSE: We sought to determine knowledge at the time of symptom onset regarding the signs, symptoms, and risk factors of stroke in patients presenting to the emergency department with potential stroke. METHODS: Patients admitted from the emergency department with possible stroke were identified prospectively. A standardized, structured interview with open-ended questions was performed within 48 hours of symptom onset to assess patients' knowledge base concerning stroke signs, symptoms, and risk factors. RESULTS: Of the 174 eligible patients, 163 patients were able to respond to the interview questions. Of these 163 patients, 39% (63) did not know a single sign or symptom of stroke. Unilateral weakness (26%) and numbness (22%) were the most frequently noted symptoms. Patients aged > or = 65 years were less likely to know a sign or symptom of stroke than those aged < 65 years (percentage not knowing a single sign or symptom, 47% versus 28%, P = .016). Similarly, 43% of patients did not know a single risk factor for stroke. The elderly were less likely to know a risk factor than their younger counterparts. CONCLUSIONS: Almost 40% of patients admitted with a possible stroke did not know the signs, symptoms, or risk factor of a stroke. Further public education is needed to increase awareness of the warning signs and risk factors of stroke.

Aged↗
PubMed1997

[Inhibition of cell growth and target gene expression of human pancreatic carcinoma cells by modified antisense oligodeoxynucleotide].

OBJECTIVE: To investigate the inhibitory effects of modified antisense oligodeoxynucleotide on cell growth, 3H-TdR incorporation rate and target gene expressions of human pancreatic carcinoma cells as a comparison with the effectiveness of nonmodified antisense oligodeoxynucleotide (ASODN) resported previously. METHODS: Synthesized modified antigsense oligodeoxynucleotides (antisense phosphorothioate oligodeoxynucleotides, ASPODN) complementary to the cap regions of c-myc and Ki-ras genes were used to treat PC-2 and PC-3 human pancreatic carcinoma cell line cells with multiple small (10 micrograms) doses or one single dose (15 micrograms). After treatment, cell growth rates and 3H-TdR incorporation rates were estimated, and the concurrent oncogene expressions were studied by adopting RT-PCR technique. RESULTS: After multiple ASPODN exposures, the cell growth rates and 3H-TdR incorporation rates were significantly inhibited, the inhibition was maintained for more than two weeks. On the 14th day, the cell growth rates of the ASPODN groups were reduced to 38%-43% of that of the controls, and the 3H-TdR incorporation rates were 18%-33% of that of the controls, there were also marked inhibition or down-regulation of target genes (c-myc and Ki-ras) expressions. After the 15 micrograms single dose treatment, the inhibition of cell growth, 3H-TdR incorporation and target gene expressions lasted for 4 days. CONCLUSIONS: The results of this study confirm the fact that ASPODN exerts a more strong inhibitory effect on pancreatic carcinoma cells than the non-modified ASODN.

Adenocarcinoma↗
PubMed1997

[The inhibitory effect of combined treatment of TNF alpha and antisense oligodeoxynucleotides on the growth of human pancreatic carcinoma cell line cells].

OBJECTIVE: To study the inhibitory effect induced by combined treatment of TNF alpha and antisense oligodeoxynucleotide on the growth of human pancreatic adenocarcinoma cell line (PC-2) cells. METHOD: TNF alpha and synthesized antisense c-myc or Ki-ras phosphorothioate oligodeoxynucleotide (ASPODN) were added to the culture media of PC-2 cells, whereas the groups treated with TNF alpha or ASPODN alone were used as controls. The cell growth rate was estimated by cell count and MTT analysis, the endogenous target gene expression was studied by adopting RT-PCR-Southern blot technique, and cell apoptosis was detected in situ. RESULTS: The cell growth was inhibited much more obviously in the groups of combined treatment than in the groups treated with TNF alpha or ASPODN alone. Marked inhibition of endogenous Ki-ras and c-myc expression was observed in the groups treated with Ki-ras and c-myc ASPODN. The amounts of apoptotic cells were 8.0% and 8.4% in the groups of TNF alpha + Ki-ras ASPODN and TNF alpha + c-myc ASPODN, and were 5.2%, 4.8% and 5.4% for TNF alpha, Ki-ras ASPODN and c-myc ASPODN respectively. CONCLUSION: Our results demonstrate that the inhibitory effect induced by combined treatment of TNF alpha and ASPODN on cell growth was stronger than that induced by TNF alpha or ASPODN alone.

Adenocarcinoma↗
PubMed1997

[Studies on gene expression of bcl-2 and its correlation with tumor cell apoptosis as well as expression of p16 in human neuroblastoma].

OBJECTIVE: To elucidate the relationship between bcl-2 gene expression and the frequency of apoptosis of tumor cells, and study the expression of p16 tumor suppressor gene in neuroblastoma. METHODS: In situ hybridization and immunohistochemistry methods were used to study the frequencies of expression of bcl-2 and p16 genes in 20 cases of neuroblastoma. Meanwhile, an in situ apoptotic cell detection method was adopted to detect the apoptotic cells in these tumors, and the number of apoptotic cells was compared with the bcl-2 gene expression in each case. RESULTS: In situ hybridization revealed that the positive frequencies of both bcl-2 and p16 gene expression in 20 neuroblastoma specimens were 95%, and the expression rates at the protein level of these 2 gene products as detected by immunohistochemistry were both 100%. There was no significant difference between the positive rates obtained by these 2 methods. Comparing the bcl-2 expression and apoptotic cell number in these specimens, we found that the apoptotic cell number increased as the level of bcl-2 expression decreased. CONCLUSIONS: The bcl-2 gene was expressed in most of human neuroblastomas. The reverse correlation of bcl-2 expression and tumor cell apoptosis further confirms that bcl-2 as an important gene inhibiting cell apoptosis may indirectly promote the carcinogenesis of neuroblastoma. It seems that there was no significant loss of p16 gene expression in these cases.

Adrenal Gland Neoplasms↗
PubMed1997

[Prenatal diagnosis and early treatment of congenital urological deformites].

11 children were treated in our hospital from 1987 to 1990 for the congenital urological defomities. They were diagnosed prenatally and were treated early after birth, and 5 of them were compared with 28 children who had been treated in the same hospital in the same stage for hydronephrosis due to the congenital pelvic-ureter stenosis, that was not prenatally diagnosed. Analysis of a series of renal functional test, special methods and clinical study, showed the possibility of prenatal diagnosis and the necessary of early treatment of congenital urological deformities.

Female↗
PubMed1997

[VATS in malignant pleural effusions].

Between November 1992 and October 1996, 20 patients with malignant pleural effusions were submitted to VATS under general anesthesia. The overall positive histological diagnoses were obtained through VATS (20/20). The malignant pleural mesothelioma in 8 cases and metastatic cancers in 12 cases were histopathologically confirmed. Talc pleurodesis was performed for all the cases, and 18 patients gained lasting pleurodesis and the other 2 patients did not. The failure of pleurodesis was due to that the lung could not reexpand to come into contact with the chest wall. Postoperative complications included transient fever and slight asthma in 2 cases, and the symptoms were relieved obviously after some simple therapy to symptom. In conclusion, VATS has provided a high positive diagnosis of patients with malignant pleural effusions not diagnosed by conventional methods and good results in pleurodesis, but some operating skills must be emphasized.

Adult↗
PubMed1997

[The effect of antibody against vascular endothelial growth factor on tumor growth].

OBJECTIVE: Vascular endothelial growth factor (VEGF) is a very important factor in the process of angiogenesis, which is chosen as a target for experimental study of anticancer. METHODS: Anti-VEGF antibody was obtained from immunized rabbits and purified with affinity column. Morever, it was identified as neutralized antibody by Mile's assay. RESULTS: The anti-VEGF antibody was able to inhibit growth of S180 sarcoma in a dose-dependent manner, and the inhibition rate reached 41.0% with dose 200 micrograms per mouse per day. For human gastric cancer (MGC-803)-bearing nude mice, Anti-VEGF antibody inhibited tumor growth by 76.2%. When anti-VEGF antibody was combined with 131I-3H11, a murine monoclonal antibody conjugated with 131I for treatment, only one of five nude mice developed tumor and 84.0% more inhibition of tumor growth was obtained in comparison with treatment by 131I-3H11 only. CONCLUSION: The anti-VEGF antibody may be potentially useful for clinical treatment of cancer.

Animals↗
PubMed1997

[Binding of oral lactobacilli to collagen].

The present study surveyed the ability, the characters and the influential factors on lactobacilli binding to the collagen. The experiment employed reference strains and fresh isolated strains. Binding of 3H-labeled bacteria to human type I collagen absorbed on hydroxyapatite surface (C-HA) was tested. The results suggested that the lactobacilli had high affinity for collagen. Competitive inhibitory assay indicated the attachment was highly specific. Binding to C-HA occurred in a collagen dose-dependent manner. pH value of reaction mixtures significantly affected the adherence. Below pH 6.5, increasing pH value caused a reduction of binding. Above pH 6.5, the binding was less affected. The ionic strength apparently influenced the binding level. The results of this study revealed one of the mechanisms that oral lactobacilli target dentin and root surfaces caries. This may also be a cariogenic virulent factor of lactobacilli.

Bacterial Adhesion↗
PubMed1997

[The study of actinomyces viscosus adhere to teeth. III. The identification of mutants of A. viscosus and preparation of rabbit IgG against type 1 and type 2 fimbriae].

The authors prepared rabbit antisera against 5519 and 5951. The IgGs against type 1, type 2 fimbriae were purified from the antisera using sera absorbed with the other strain and IgG purification method. It was identified by SDS-PAGE and ELISA. This result suggested the purified proteins were the IgG against type 1 and type 2 fimbriae.

Actinomyces viscosus↗
PubMed1997

[The study of actinomyces viscosus adhere to teeth. IV. The study of salivary protein receptors of A. viscosus].

In order to determine the receptors of A. viscosus for adhesion, 7 kinds of main purified proteins from pellicle formed by whole saliva were tested. The result indicated that: 1. APRP, statherin, PRPG and SIgA were the receptors of standard and fresh isolated A. viscosus; 2. APRP and stather promoted the adherence of 5519 (1+2-) to HA, and SIgA promoted the adherence 5951 (1-2+) to HA; PRPG was the common receptor of the two fimbriae. It suggested that there were receptors not only type 1 fimbriae but also type 2 in pellicle. Two types of fimbriae were involved in the adherence of A. viscosus to pellicle. The difference existed in the receptor of adherence and the activity site of the same receptor.

Actinomyces viscosus↗
PubMed1997

[Study on the relationship between the expression of adhesion molecules and the invasiveness of acute myeloid leukemia cells].

OBJECTIVE: To study the relationship between the expression of adhesion molecules CD49d (VLA-4) and CD11a (LFA-1) and the invasiveness of acute myeloid leukemia (AML) cells. METHODS: Peripheral blood and/or bone marrow samples from 50 AML patients were investigated by APAAP and Western blotting method. RESULTS: Extramedullary invasion developed in 32 of 50 patients (64%). The expression of CD49d and CD11a in the invasive group was much higher than that in the non-invasive group (P<0.005), while the difference between the leukemic cells from bone marrow and peripheral blood for CD49d/CD11a expression was not significant. CONCLUSION: AML cells might adhere to and get through vascular endothelium by CD49d/VCAM-1 and CD11a/ICAM-1 adhesion mechanism, and the expressions of CD49d and CD11a were not critically responsible for the release of leukemic cells from bone marrow.

Adolescent↗
PubMed1997

[The method for studying kinetics of formation reaction of complex in dimeric system].

The method for studying kinetics of formation reaction of complex in aggregation system was reported in this paper. The concentration of more than one species was calculated by improved method for calculating dimeration constants. Kinetics of reaction between Cu (II) and tri-sulfophthalocyanine (S3Pc) was studied in this way. It shows that the rate of reaction between Cu(II) and S3Pc can be expressed as follows: v = K[Cu][S3Pc]

Copper↗