Structural and functional analysis of pantocin A: an antibiotic from Pantoea agglomerans discovered by heterologous expression of cloned genes.
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Anti-Bacterial Agents↗
Biomedical subjects
Liang Liu
Publications and source records attributed to Liang Liu.
Direct observations of the cleavage reaction of an L-DPPC monolayer catalyzed by phospholipase A2 and inhibited by an indole inhibitor at the air/water interface.
The enzymatic hydrolysis of an L-dipalmitoylphosphatidylcholine (L-DPPC) monolayer at the air/water interface, catalyzed by phospholipase A(2) (PLA(2)), serves as a model for biospecific interfacial reactions. The cleavage of L-DPPC was investigated by Brewster angle microscopy. Different types of domain defects were observed to form in the coexisting liquid expanded and liquid condensed phases during the hydrolysis reaction. The adsorption of the enzyme was quantitatively recorded as the increase of the surface pressure over a fixed molecular area with time. In the case of L-DPPC, the surface pressure first increases and then starts to decrease, which indicates that a soluble product (lysolipid) is produced during the catalytic cleavage reaction. The increase and decrease of the surface pressure, which corresponds to the change of shape and number density of domains, indicated the occurrence of the following processes: adsorption of PLA(2), cleavage reaction, and rearrangement of substrate and product molecules at the interface. Addition of a PLA(2) inhibitor to the lipid monolayer leads to a fast surface pressure increase after enzyme injection. The surface pressure reaches a maximum value and then does not change for a long time. During this period, no change in the domain shape and number density was observed, which indicates that the enzyme is inhibited for a certain period of time. The experimental results provide the possibility of a direct way to prove inhibitor activity.
1,2-Dipalmitoylphosphatidylcholine↗
Aging, cancer and nutrition: the DNA methylation connection.
Cancer and aging are two coupled developmental processes as reflected by the higher incidence of cancer in the elderly human population group. Genetic mutations accumulate in somatic cells with age, which may explain in part the association of age with cancer. Epigenetic mechanisms are also frequently involved in controlling gene functions during development and tumorigenesis. A common molecular feature associated with both aging and tumorigenesis is global hypomethylation of the genomic DNA. The contributing mechanisms underlying this hypomethylation are not yet well understood. Epigenetic investigation of cancer and aging has recently emerged as a fruitful area of study and has added exciting insights into some of the mysteries surrounding aging and cancer. Recent studies have also shown that dietary factors can modulate DNA methylation and thereby contribute to aging and tumorigenesis. Thus, DNA methylation provides an important common link between aging, cancer and nutrition.
Aging↗
Hyper-polyhedron model applied to molecular screening of guanidines as Na/H exchange inhibitors.
AIM: To investigate structure-activity relationships of N-(3-Oxo-3,4-dihydro-2H-benzo[1,4]oxazine-6-carbonyl) guanidines in Na/H exchange inhibitory activities and probe into a new method of the computer-aided molecular screening. METHODS: The hyper-polyhedron model (HPM) was proposed in our lab. RESULTS: The samples with probably higher activities could be determined in such a way that their representing points should be in the hyper-polyhedron region where all known samples with high activities were distributed. And the predictive ability of different methods available was tested by the cross-validation experiment. CONCLUSION: The accurate rate of molecular screening of N-(3-Oxo-3,4-dihydro-2H-benzo[1,4]oxazine-6-carbonyl) guanidines by HPM was much higher than that obtained by PCA (principal component analysis) and Fisher methods for the data set available here. Therefore, HPM could be used as a powerful tool for screening new compounds with probably higher activities.
Computer-Aided Design↗
Correlation between shear induced platelet aggregation and viscosity parameter for platelet-rich plasma.
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Animals↗
[Clinicopathologic analysis of 154 cases of tumors and tumor-like lesions in the bones of hands and feet].
OBJECTIVE: To study the clinical and pathologic features of tumors and tumor-like lesions in the bones of hands and feet. METHODS: Clinical, X-ray and pathologic features of 154 cases of tumors and tumor-like lesions in the bones of hands and feet between 1991 and 2002 were investigated. RESULTS: In the bones of hands and feet the frequency and distribution of many lesions were distinctive when compared to those of other skeletal sites. Cartilaginous lesions were most common (60%), and 72% of them were enchondromas. Enchondromas were most often situated in the second to fifth phalanges and metacarpal bones. Chondroblastomas most frequently involved the irregular bones (such as calcaneus, talus and osnaviculare) of the feet. Whereas the occurance of osteochondromas in the bones of the hands and feet was lower than in the long bones. Most "osteochondromas" of the phalanges were subungual exostoses. A group of reactive or reparative lesions, which are related to trauma, such as subungual exostosis, giant cell reparative granuloma, florid reactive periostitis and bizarre parosteal osteochondromatous proliferations typically occurred in the bones of the hands and feet, but these tumor-like lesions were often misdiagnosted. Another feature of lesions in the bones of the hands and feet was that there were much more benign than malignant lesions (21:1), and that chondrosarcomas were common in malignancies. The diagnostic criteria for benign and malignant cartilaginous tumors in the bones of hands and feet were different from those in long bones and flat bones. CONCLUSIONS: Bone tumors of the hands and feet are different from that of long bones, flat bones and axial bones. Because the hands and feet are frequently exposed to trauma, reactive and reparative lesions often occur in these sites. These tumor-like lesions may simulate benign and malignant neoplasia. Knowledge of different types of lesions which commonly affect these sites is of benefit in assessing lesions of the bones of hands and feet.
Bone Neoplasms↗
The kinetics of deregulation of expression by de novo methylation of the h19 imprinting control region in cancer cells.
Epigenetic lesions are common in neoplasia and range from hypermethylation of subsets of CpG islands to loss of imprinting. By exploiting an episomal model system and the strong de novo methylation capacity of a human cancer cell line, we show that an H19 minigene rapidly becomes methylated and silenced, mimicking the inactivation of the maternal H19 allele in a range of cancers. Although the H19 imprinting control region (ICR) initially displayed methylation protection, it eventually succumbed to the pressure mounted by the de novo methylation machinery of the JEG-3 cells. Importantly, we were able to visualize the kinetics of the loss of the H19 ICR chromatin insulator function in association with chromatin compaction. Our results document that a strong de novo methylation machinery leads to loss of methylation privilege states of H19 ICR to functionally manifest loss of insulator function in a matter of only a few days in human cancer cells.
Animals↗
[The applying and foreground of quantifying DNA content by image analysis technique in determining postmortem interval].
Image Analysis Technique(IAT) was developed at 1950's, which quantifies the changing all the part of image by sampling, processing, quantifying, computing, analyzing the information of image. And now it has become a normal quantifying technique in biology and medicine research. In the present paper, we reviewed briefly the principium of quantifying the DNA content by IAT, the law of degradation of DNA in nucleus and the foreground of this method in determining PMI in forensic pathology.
DNA↗
[The mast cell and trauma].
Mast cell(MC) takes an important role in trauma and the process of wound healing, and the pathophysiology reaction has a relationship to the time since trauma, which is helpful to determine the post-trauma and postmortem interval, and to distinguish the wound shaped whether before or after death. In this paper, the role of MC and its chemic medium in the process of wound healing, scar shaping, postburns inflammatory response, healing of bone fracture, as well as the signification for forensic medicine and the progress of researching in this field were reviewed.
Burns↗
[Pathologic diagnosis and histogenesis of primary signet ring cell carcinoma of the prostate].
OBJECTIVE: To study the histogenesis, pathologic features and differential diagnosis of prostatic primary signet ring cell carcinoma. METHODS: 10 cases of the primary signet ring cell carcinoma were detected from 262 cases of prostate carcinomas diagnosed on needle biopsy were investigated by routine pathological, immunohistochemical and histochemical methods, and then compared with 10 cases of signet ring cell carcinomas of the stomach and colon. 3 cases were studied with electron microscopy. RESULTS: 9 cases of prostate signet ring cell carcinoma were associated with concurrent high-grade conventional prostatic carcinoma, but at least 25% of the neoplasm consisted of signet ring cells. Only one case was pure signet ring cell carcinoma. Neoplastic signet ring cells may be divided into two types: the first type showed formation of intracytoplasmic lumina or vacuole, and the second type had intracytoplasmic accumulation of excess PSA and/or PAP. Both types of signet ring cells were negative for mucin staining (AB/PAS and mucicarmine). Therefore they differed from signet ring cell carcinomas of the stomach and colon. CONCLUSIONS: Primary prostate signet ring cell carcinoma is a low-differentiated adenocarcinoma of a special histologic type, which arises from the epithelial cells of the prostate acinus. They can be distinguished from metastatic signet ring cell carcinoma of the stomach and colon and also from vacuolate degeneration of conventional carcinoma after endocrine or radiation therapy.
Carcinoma, Signet Ring Cell↗
Quantification of Aconitum alkaloids in aconite roots by a modified RP-HPLC method.
The three Aconitum alkaloids, aconitine (1), mesaconitine (2) and hypaconitine (3), are pharmacologically active but also highly toxic. A standardised method is needed for assessing the levels of these alkaloids in aconite roots in order to ensure the safe use of these plant materials as medicinal herbs. By optimising extraction, separation and measurement conditions, a reliable, reproducible and accurate method for the quantitative determination of all three Aconitum alkaloids in unprocessed and processed aconite roots has been developed. This method should be appropriate for use in the quality control of Aconitum products. The three Aconitum alkaloids were separated by a modified HPLC method employing a C18 column gradient eluted with acetonitrile and ammonium bicarbonate buffer. Quantification of Aconitum alkaloids, detected at 240 nm, in different batches of samples showed that the content of 1, 2 and 3 varied significantly. In general, the alkaloid content of unprocessed roots was higher than that of processed roots. These variations were considered to be the result of differences in species, processing methods and places of origin of the samples.
Aconitine↗
Expression of estrogen receptor-beta isoforms in Barrett's metaplasia, dysplasia and esophageal adenocarcinoma.
We have previously shown that the majority of esophageal adenocarcinomas (EA), and its precursor Barrett's metaplasia (BM), express estrogen receptor beta (ER-B). Several isoforms of ER-B have been described and are presumed to have different functions, but their distribution in BM and EA is not known. The aim of this work was to determine which ER-B isoforms are expressed in EA and BM. Sections of formalin-fixed and paraffin-embedded esophageal tissue from 33 esophageactomy specimens, of which 27 had invasive EA, were stained for the ER-B isoforms ER-B1, ER-B2, ER-B3 and ER-B5 utilizing the immunoperoxidase method ER-B1 was detected in 23 out of 27 (85%) EA compared to 3 out of 14 (21%) Barrett's metaplasia negative for dysplasia (BMND) (p =0. 0001); ER-B2 was expressed in 22 out of 27 (81%) EA in contrast to 3 out of 14 (21%) BMND (p=0.0004); ER-B3 was positive in 27 out of 27 (100%) EA in contrast to only 1 out of 14 (7%) BMND (p<0001); ER-B5 was detected in 27 out of 27 (100%) EA compared to 9 out of 14 (62%) of BMND (p=0.0027). High- and low-grade dysplasia showed a similar ER-beta isoform expression profile to that of EA Cancers invasive through the esophageal wall had a higher percent of cells with cytoplasmic expression of ER-B1 than tumors limited to the wall (T3 vs. T1 and T2, p=0.051). We conclude that ER-B1, ER-B2, ER-B3 and ER-B5 are overexpressed in EA compared to its precursor lesion BMND, suggesting a significant biological role for steroid hormones in EA.
Adenocarcinoma↗