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Biomedical subjects

P Fu

Publications and source records attributed to P Fu.

At least 55 records · Page 3Linked to original sources
PubMed1999

[Pathogenic gene analysis of Listeria isolated from foods].

In 1996-1997, Listeria in foods from 12 provinces of China were detected by using the national standard examination method GB 4789.30-94 (routine traditional methods). Twenty four strains Listeria monocytogenes and 141 strains Listeria were identified by biochemical procedures and animal toxicity experiment. Polymerase Chain Reaction(PCR) was used to amplify two specific DNA fragments(719 bp and 446 bp) of listeriolysin O and internalin genes with two pairs of primer--Hly1-2 and Inl1-2, respectively. The experiment results showed that 57 strains contained only internalin, 27 strains contained both internalin and listeriolysin O from the pathogenic genes of isolated strains.

Animals↗
PubMed1998

Analytical shape computation of macromolecules: I. Molecular area and volume through alpha shape.

The size and shape of macromolecules such as proteins and nucleic acids play an important role in their functions. Prior efforts to quantify these properties have been based on various discretization or tessellation procedures involving analytical or numerical computations. In this article, we present an analytically exact method for computing the metric properties of macromolecules based on the alpha shape theory. This method uses the duality between alpha complex and the weighted Voronoi decomposition of a molecule. We describe the intuitive ideas and concepts behind the alpha shape theory and the algorithm for computing areas and volumes of macromolecules. We apply our method to compute areas and volumes of a number of protein systems. We also discuss several difficulties commonly encountered in molecular shape computations and outline methods to overcome these problems.

Algorithms↗
PubMed1998

Analytical shape computation of macromolecules: II. Inaccessible cavities in proteins.

The structures of proteins are well-packed, yet they contain numerous cavities which play key roles in accommodating small molecules, or enabling conformational changes. From high-resolution structures it is possible to identify these cavities. We have developed a precise algorithm based on alpha shapes for measuring space-filling-based molecular models (such as van der Waals, solvent accessible, and molecular surface descriptions). We applied this method for accurate computation of the surface area and volume of cavities in several proteins. In addition, all of the atoms/residues lining the cavities are identified. We use this method to study the structure and the stability of proteins, as well as to locate cavities that could contain structural water molecules in the proton transport pathway in the membrane protein bacteriorhodopsin.

Algorithms↗
PubMed1998

Why is a pomegranate an apple? The role of shape, taxonomic relatedness, and prior lexical knowledge in children's overextensions of apple and dog.

Children's overextensions (e.g. referring to a pomegranate as apple) raise intriguing questions regarding early word meanings. Specifically, how do object shape, taxonomic relatedness, and prior lexical knowledge influence children's overextensions? The present study sheds new light on this issue by presenting items that disentangle the three factors of shape, taxonomic category, and prior lexical knowledge, and by using a novel comprehension task (the screened-alternative task) in which children can indicate negative exemplars (e.g. which items are NOT apples). 49 subjects in three age groups participated (Ms = 2;0, 2;6, and 4;5). Findings indicate: (1) Error patterns differed by task. In production, errors were overwhelmingly due to selecting items that matched the target word in BOTH shape and taxonomic relatedness. In comprehension, more errors were based on either shape alone or taxonomic relatedness alone, and the nature and frequency of the overextensions interacted with prior lexical knowledge. (2) Error patterns also differed markedly based on the word being tested (apple vs. dog), in both comprehension and production (3) As predicted, errors were more frequent in production than comprehension, though only for children in the two younger age groups. Altogether, the study indicates that overextensions are not simply production errors, and that both taxonomic relatedness and object shape play a powerful role in early naming errors.

Age Factors↗
PubMed1998

[An in vitro of acrylonitrile inducing early damage on buccal mucosa of murine]

ObJECTIVE:Understand the change and damage of rats and mice buccal mucosa tissue structure posioned by acrylonitrile and alcohol. METHODS: Using optical microscope and transmitted electron microscope (TEM) techniques, observed the structure of rats and mice buccal mucosa which posioned by acrylonitrile and alcohol for 13 weeks in different dosages. RESULTS: Acrylonitrile can damage the ultrastructure of the cells and lead to precancerous dysplasia,such as enlargement and deformation of nuclei, reducing of desmosomes and hemidesmosomes,break of basement membrane,swelling and denaturalization of mitochondrion. The degree of damage was correlated with its dosage. Alcohol can increase the damage caused by acrylonitrile. CONCLUSION: Both acrylonitrile and alcohol can destroy the ultrastructure of cells,TEM is helpful for diagnosing disease in their early stage,and buccal mucosa can be used as a window for observing the disease caused by many toxic factors.

Journal Article↗
PubMed1998

[Effect of changes of amino acids of N-terminal region of the mature protein on secretion of alpha-amylase in B. subtilis].

The mutant plasmid pAmy413C, in which G takes the place of A at the 271 position of alpha-amylase gene on the pAmy413 from B. licheniformis, was constructed by site-direct mutagenesis. At the N-terminus of the mature alpha-amylase, amino acid +2Asn was substituted by +3Asp in the wild type protein. Then, the alpha-amylase output of the mutant plasmid pAmy413C in B. subtilis was 2.02-2.57 times higher than that of the wild type pAmy413C in the same strain. The amino acid sequencing at the N-terminus of the matural alpha-amylase revealsed that the recognition site of signal peptidase I moved one amino acid upstream, from Ala-(+2)Asn to AlaAla-(+3) Asp. That is, the +2Asn of the wild type was changed to the +3Asp of the mutant. The secondary structural analysis showed that a 14-cycle structure formed in the alpha-amylase mRNA when the free energy was -51.7 kcal. In this case, the mutant is identical with the wild type. The difference between them is that G at 271 position is no longer paired with U at 211 position, hence, a G-overhang is formed. The secondary structural analysis of protein showed that one amino acid diminished in the turn structure of amino acid at 33-37 position, and this very amino acid is involed in an alpha-helix structure. In short, all the changes mentioned above in conformation and charged amino acids contribute to the increase in the protein secretion in B. subtilis.

Amino Acid Sequence↗
PubMed1997

Experimental study on modified treatment and endothelialization of bovine pericardial valves.

The purpose of this study were to confirm whether the modified treatment with L-glutamic acid could attenuate the calcification of the GA-fixed valves and improve its biocompatibility. Pericardial valves were routinely treated with GA and valves were treated with GA and 8% L-glutamic acid. The valves treated with these methods were implanted subcutaneously in rats. Calcium deposits of the valves collected at the 7th, 21st, 60th, 90th day were assessed by atomic absorption spectroscopy, and the pathologic changes were examined by light and electron microscopy. Cultured endothelial cells (ECs) were seeded onto the valves. The cell counts were determined at the 1st, 4th, 7th, 10th day after seeding. PGI2 in culture medium was tested at the 10th day. Transmission and scanning electron microscopy were used to observe the growth of ECs on the valves. Results showed that subsequent treatment with L-glutamic acid could significantly mitigate calcification of bovine pericardial valves as compared with simple GA-fixed valves (P < 0.01). ECs seeded on the GA treated valves died within 4 days. On the valves treated by modified method, ECs could proliferate and release PGI2. It is concluded that treatment with L-glutamic acid can markedly inhibit the calcification and improve the biocompatibility of bioprosthetical valves.

Animals↗
PubMed1997

Effect of amino acid cardioplegia on myocardial metabolism and function of ischemic canine heart.

To evaluate the effect of amino acid cardioplegia on myocardial metabolism and function of ischemic canine heart, canine cardiopulmonary bypass (CPB) model was established and the dog heart was subjected to a 120 min ischemic arrest. Animals were divided into 3 groups, group 1: warm blood cardioplegia induction and terminal perfusion plus 4 C ST. Thomas hospital solution (STS) during ischemia; group 2: warm blood cardioplegia enriched with amino acid (L-asparte and L-glutamate 13 mmol/L each) and STS without amino acid (A. G.) and group 3: both warm blood cardioplegic solution and STS enriched with A. G. . The result demonstrated that the cardiac function of animals in group 2 and 3 had a significantly better recovery after ischemic-re-perfusion. By the end of ischemia the content of myocardial ATP in group 3 was distinctly higher than that in group 1 (P < 0.05), with the release of cardiac enzyme being the least. Myocardial ultra-structure almost remained intact before and after ischemia. Our experiment suggests that the cardioplegia arrest with warm blood and cold crystalloid solution enriched with amino acids could diminish the ischemia-re-perfusion injuries of the heart and enhance the effect of myocardial protection.

Amino Acids↗
PubMed1997

[L-arginine and nitric oxide have effects on glomerulus hyperperfusion of early diabetic rats].

We used streptozotocin (STZ) to induce the animal model of diabetes mellitus in rats. On the 7th and 14th days of induction, kidney disorder, the levels of NO3- in plasma and tissue homogenate in different periods were observed. The NO3- levels in relation to the application of L-arginine (L-Arg) were also noted. The results showed that the kidney weight/body weight ratio significantly increased in different periods (P < 0.05). On the 7th day profuse proteinuria appeared and it markedly increased on the 14th day: creatinine clearance rate (Ccr) significantly raised, too (P < 0.005). The NO3- levels in plasma and tissue homogenate were getting higher with time. The level of NO3- significantly increased after L-Arg was perfused. It indicated that kidney disorder was present at the early stage of diabetes, and the raised Ccr indirectly indicated the increase of glomerular filtration rate. These suggest that NO3- and L-Arg may be important mediums which have effects of hyperfiltration and hyperperfusion of glomerulus.

Animals↗
PubMed1996

Expression of human relaxin genes: characterization of a novel alternatively-spliced human relaxin mRNA species.

Relaxin is a two-chain peptide hormone encoded by two non-allelic genes in humans and great apes, and by a single gene in all other species studied. We have characterized the expression of the human relaxin genes (H1 and H2) in placenta, decidua, prostate and ovary by reverse-transcription/polymerase chain reaction (RT/PCR). H2 relaxin mRNA was detected in the ovary, term placenta, decidua, and prostate gland. In contrast, H1 gene expression was detected only in the prostate gland. In addition to the relaxin PCR product of the predicted size (486 bp), a larger relaxin-specific product (587 bp) was detected in both H1 and H2 amplifications and in amplifications of chimpanzee relaxin from placenta and corpus luteum. Sequencing of human and chimpanzee PCR products, and human relaxin genomic clones, revealed that the larger product arises from an alternatively-spliced relaxin mRNA species incorporating an extra exon. This is the first evidence that the structure of the human and chimpanzee relaxin genes differ from that of other characterized relaxin genes, such as pig and rat. The novel peptide arising from this alternate message would be identical to prorelaxin in the B-chain and part of the C-peptide (extending to the position of the intron) but would differ from prorelaxin in the carboxy-terminal domain. Observation of a similar mRNA species in the chimpanzee suggests that this conserved relaxin-like peptide may have a significant biological role.

Alternative Splicing↗
PubMed1996

Mallory body induction in drug-primed mouse liver.

The aim of this study was to determine the various factors that are involved in the induction of Mallory body (MB) formation. A model was developed where MB formation was induced by refeeding either of the drugs griseofulvin or diethyl 1,4-dihydro-1,4,6-trimethyl-3,5-pyridinedicarboxylate (DDC). Mice were fed the drugs for 5 months, followed by withdrawal of the drugs for 1 month (drug-primed livers). The drugs were refed for 1,3,5,7, or 11 days. Early MBs first appeared as small, enlarged aggregates of filaments in the perinuclear or pericanalicular location on the third day of refeeding. Mature MBs appeared on the fifth day of refeeding. MBs reached maximum concentration on day 5 of refeeding. Western blots showed a progressive increase in the cytokeratin proteins (CK49 and CK55) and actin while refeeding the drugs. Liver cell regeneration, as indicated by the percent of proliferating cell nuclear antigen (PCNA)-positive nuclei, increased on the third day of refeeding. However, there was no correlation between the frequency of MBs and the percent of PCNA-positive nuclei. It is concluded that MB formation is not related to the liver cell regeneration response to injury but rather involves a separate regulation pathway. The MBs were heavily ubiquitinated and were associated with increased ubiquitin-protein conjugates as indicated by Western blotting, suggesting that ubiquitinization of cytokeratin protein are involved in the formation of MB aggregation.

Animals↗
PubMed1996

The observation of complement activation and polymorphonuclear neutrocytopenia during cardiopulmonary bypass.

By determining the plasma levels of C2, C4, factor B and polymorphonuclear neutrophils (PMNs) of the patients who received CPB, the path of complement activation and changes of PMNs were studied. The results suggest that complement system was activated through alternative pathway during CPB and was activated through classic pathway after CPB. The anaphylatoxin, the products of complement activation may be responsible for the polymorphonuclear neutrocytopenia.

Adolescent↗
PubMed1996

Antioxidant status in persons with and without senile lens changes.

Biochemical evidence on lens culture suggests that antioxidant nutrients can protect lens against peroxidation caused by radiation. A case-control study was carried out on 262 middle aged (45-54) and aged (55-64) subjects. The relationship between biochemical markers of antioxidant status and senile lens changes (including cataract) was examined in 131 subjects with senile lens changes and 131 control subjects with clear lens. Antioxidant status was measured using plasma and erythrocyte glutathione peroxidase, erythrocyte superoxide dismutase and catalase activity and plasma levels of vitamin E and vitamin A. Subjects were grouped by age and sex. The results were as follows: (1) The subjects with lens changes tended to have lower plasma levels of vitamin E and vitamin A, lower activity of several antioxidant enzymes and higher level of MDA. (2) The subjects with senile lens changes had significantly lower erythrocyte glutathione peroxidase level. (3) In the middle-aged group, subjects with senile lens changes were observed to have lower erythrocyte and plasma glutathione peroxidase level than those without senile lens changes. The results suggest that appropriate amount of antioxidant nutrients might be expected to prevent or retard the process of lens changes.

Aging↗
PubMed1995

Comparison of lithium ratio between African-American and Caucasian bipolar patients.

Lithium RBC/plasma ratio (LR) was studied in 34 bipolar subjects on therapeutic doses of lithium carbonate. The sample was divided into 22 Caucasians and 12 African-Americans to observe possible ethnic differences in LR as previously reported. The latter group demonstrated a higher LR as well as increased reports of side effects (p < .05), even after controlling previous confounding factors. Our findings suggest that African-Americans may be more susceptible to the side effects associated with lithium treatment, and consequently, lower dosages may be necessary for this group.

Adult↗
PubMed1995

Heat shock in vivo induces Mallory body formation in drug primed mouse liver.

Perturbations in keratin intermediate filament organization and Mallory body (MB) formation are associated with alcoholic hepatitis. Inducible heat shock proteins (HSPs) are expressed in a variety of liver diseases including alcoholic liver disease. Therefore, we investigated whether heat shock protein induction can lead to MB formation. Mice were primed by a 5-month feeding of griseofulvin (GF) or diethyl 1,4-dehydro-2,4,6-trimethyl-3,5-pyridinedicarboxylate (DDC) followed by drug withdrawal for 1 month. The animals were then subjected to an in vivo heat shock treatment or sham heat treatment. Liver morphology, HSP expression, liver regeneration (PCNA-labeled nuclei), and MB formation were monitored during a 7-day posttreatment period. Numerous MBs developed in the livers of mice exposed to GF or DDC for 5 months, but very few small MBs remained after 1-month withdrawal of either drug. No MBs were found at Day 1 post heat shock, whereas numerous MBs were observed at Day 7. The frequency of PCNA-labeled nuclei increased during the same period. At Day 1 posttreatment, a variable liver centrilobular necrosis was observed accompanied by a prominent increase in HSP-25 and HSP70 expression, but HSP-90 expression was not increased. In drug-primed mouse liver, a heat shock treatment induces the expression of specific HSPs prior to the formation of MBs, indicating that HSP expression may play a role in the pathogenesis of MB formation. We speculate that this role is through the protein unfolding function of HSP, which leads to the aggregation of the cytokeratins to form MBs as well as to polyubiquitin binding to these proteins in a manner analogous to amyloid formation.

Animals↗