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H An

Publications and source records attributed to H An.

At least 37 records · Page 2Linked to original sources
PubMed2000

Presence of the LEE (locus of enterocyte effacement) in pig attaching and effacing Escherichia coli and characterization of eae, espA, espB and espD genes of PEPEC (pig EPEC) strain 1390.

In the present study, attaching and effacing Escherichia coli (AEEC) O45 isolates from post-weaning pigs with diarrhoea were examined for the presence of the LEE (locus of enterocyte effacement) using various DNA probes derived from the LEE of human enteropathogenic E. coli (EPEC) strain E2348/69. The LEE fragment was conserved among the eae -positive pig isolates. The attaching and effacing activity of PEPEC (pig EPEC) O45 isolates is highly correlated with the presence of the LEE. Nevertheless, for some PEPEC isolates, the insertion site of the LEE is different or has diverged during evolution. The presence of the LEE fragment in PEPEC isolates provides further evidence that the LEE region is conserved among AEEC of different animal origins. In addition, the nucleotide sequence of the region containing the eae gene and esp genes of a pig AEEC isolate, strain 1390, was determined. Among examined Eae proteins, Eae of strain 1390 showed the highest similarity with Eae belonging to the beta intimin group such as the Eae of rabbit AEEC. Moreover, all pig strains that produced attaching and effacing lesions in piglets and pig ileal explants belonged to the beta intimin group. The deduced amino acid sequences of the EspA, EspB and EspD proteins of strain 1390 showed particularly strong homology to those of AEEC strains presenting a beta intimin allele. Thus, pig AEEC possess the LEE sequences, and for the strain 1390, sequences of the eae and esp regions are related to those of other AEEC, in particular, strains presenting a beta intimin allele, such as the rabbit AEEC.

Adhesins, Bacterial↗
PubMed2000

Rainbow trout (Oncorhynchus mykiss) cystatin C: expression in Escherichia coli and properties of the recombinant protease inhibitor.

Cystatins are a superfamily of low Ki cysteine proteinase inhibitors found in both plants and animals. Cystatin C, a secreted molecule of this family, is of interest from biochemical and evolutionary points of view, and also has biotechnological applications. Recently we cloned and sequenced the cDNA for rainbow trout (Oncorhynchus mykiss) cystatin C [Li et al., 1998. Molecular cloning, sequence analysis and expression distribution of rainbow trout (Oncorhynchus mykiss) cystatin C. Comp. Biochem. Phys. B 121, 135-143]. To explore the relationship between protein structure and function of trout cystatin C, we established a bacterial system for expression of the protein. Trout cystatin C expressed in the cytoplasm of bacterial cells did not have detectable protease inhibitory activity. Activity was regained by Ni-NTA chromatography under denaturing conditions followed by dialysis-based refolding. Titration of purified cystatin C preparations with papain indicated that approximately 20% of the total protein had been converted to the active form after one refolding cycle. Expression levels were 3-5 mg/l. The protease-inhibitory properties of recombinant trout cystatin C were similar to those of human and chicken cystatin C derived from biological sources and recombinant cystatin C derived from rat and mouse genes. The Ki for papain was 1.2 x 10(-15) M, exhibiting the high affinity binding unique to this family of protease inhibitors.

Animals↗
PubMed2000

Physicochemical changes and mechanism of heat-induced gelation of arrowtooth flounder myosin.

Physicochemical changes of myosin during heating were investigated to elucidate the mechanism of heat-induced gelation of arrowtooth flounder (ATF) myosin at high ionic strength. Changes in dynamic properties indicated ATF myosin formed a gel in three different stages as shown by the first increase in G' (storage modulus) at 28 degrees C, followed by the decrease at 35 degrees C and the second increase at 42 degrees C. DSC thermogram showed the onset of myosin denaturation at 25 degrees C with two maximum transition temperatures at 30 and 36 degrees C. The decrease in alpha-helical content indicated ATF myosin began to unfold at 15 degrees C and the unfolding continued until it reached 65 degrees C. Turbidity measurement showed myosin began to aggregate at 23 degrees C and the aggregation was complete at 40 degrees C. Surface hydrophobicity increased consistently in the temperature range studied, 20-65 degrees C. Sulfhydryl contents decreased significantly at 20-30 degrees C due to the formation of disulfide linkages but remained constant at temperatures >30 degrees C. ATF myosin was shown to be extremely sensitive to heat, resulting in denaturation at lower temperature than other fish myosin. Denaturation was initiated by unfolding of the alpha-helical region in myosin followed by exposure of hydrophobic and sulfhydryl residues, which are subsequently involved in aggregation and gelation processes.

Animals↗
PubMed2000

Effects of proteolysis and mechanism of gel weakening in heat-induced gelation of fish myosin.

Addition of papain decreased the onset temperature and the rate at which G' developed during heat-induced gelation of arrowtooth flounder myosin. Frequency sweep results revealed that G' markedly decreased in proportion to the amount of papain added. However, use of E-64, a cysteine proteinase inhibitor, reversed the effects of papain and protected myosin heavy chain from degradation. DSC thermograms indicated papain significantly decreased the enthalpy required to induce myosin denaturation without significant changes in onset and maximum transition temperatures. Thermal denaturation kinetics indicated decreases in both the activation energy and the rate of myosin denaturation. CD studies revealed a rapid decrease in alpha-helical content, indicating the initial degradation of myosin molecules mostly occurred in the tail region. These results suggested that proteolysis affected thermal properties and reactivity of myosin during heating. Although myosin gel could be formed, structural disruption resulted in lower gelling ability and rigidity of the formed gel.

Animals↗
PubMed2000

A comparison of subset selection and analysis of covariance for the adjustment of confounders.

Two common methods for adjusting group comparisons for differences in the distribution of confounders, namely analysis of covariance (ANCOVA) and subset selection, are compared using real examples from neuropsychology, theory, and simulations. ANCOVA has potential pitfalls, but the blanket rejection of the method in some areas of empirical psychology is not justified. Assumptions of the methods are reviewed, with issues of selection bias, nonlinearity, and interaction emphasized. Advantages of ANCOVA include better power, improved ability to detect and estimate interactions, and the availability of extensions to deal with measurement error in the covariates. Forms of ANCOVA are advocated that relax the standard assumption of linearity between the outcome and covariates. Specifically, a version of ANCOVA that models the relationship between the covariate and the outcome through cubic spline with fixed knots outperforms other methods in simulations.

Analysis of Variance↗
PubMed2000

Quantitative measurements of cerebral blood oxygen saturation using magnetic resonance imaging.

A quantitative estimate of cerebral blood oxygen saturation is of critical importance in the investigation of cerebrovascular disease because of the fact that it could potentially provide information on tissue viability in vivo. In the current study, a multi-echo gradient and spin echo magnetic resonance imaging sequence was used to acquire images from eight normal volunteer subjects. All images were acquired on a Siemens 1.5T Symphony whole-body scanner (Siemens, Erlangen, Germany). A theoretical signal model, which describes the signal dephasing phenomena in the presence of deoxyhemoglobin, was used for postprocessing of the acquired images and obtaining a quantitative measurement of cerebral blood oxygen saturation in vivo. With a region-of-interest analysis, a mean cerebral blood oxygen saturation of 58.4%+/-1.8% was obtained in the brain parenchyma from all volunteers. It is in excellent agreement with the known cerebral blood oxygen saturation under normal physiologic conditions in humans. Although further studies are needed to overcome some of the confounding factors affecting the estimates of cerebral blood oxygen saturation, these preliminary results are encouraging and should open a new avenue for the noninvasive investigation of cerebral oxygen metabolism under different pathophysiologic conditions using a magnetic resonance imaging approach.

Cerebrovascular Circulation↗
PubMed2000

Histamine and biogenic amine production by Morganella morganii isolated from temperature-abused albacore.

Histamine-producing bacteria were isolated from albacore stored at 0, 25, 30, and 37 degrees C. They were screened using Niven's differential medium, and their histamine production was confirmed by high-pressure liquid chromatography analysis. The optimum temperature for growth of histamine-producing bacteria was 25 degrees C. The bacterium producing the highest level of histamine was isolated from fish abused at 25 degrees C. It was identified as Morganella morganii by morphological, cultural, biochemical, and antimicrobial characteristics and by the Vitek microbial identification system. The M. morganii isolate was inoculated into tuna fish infusion broth medium, and the effect of temperature was determined for microbial growth and formation of histamine and other biogenic amines. The isolate produced the highest level of histamine, 5,253 ppm, at 25 degrees C in the stationary phase. At 15 degrees C, histamine production was reduced to 2,769 ppm. Neither microbial growth nor histamine formation was detected at 4 degrees C. To determine whether the isolate can also produce other biogenic amines that can potentiate histamine toxicity, production of cadaverine, putrescine, serotonin, tryptamine, tyramine, phenylethylamine, spermidine, and spermine by the isolate was also monitored. Cadaverine, putrescine, and phenylethylamine were detected with microbial growth in the tuna fish infusion broth medium. The optimum temperature for cadaverine, putrescine, and phenylethylamine formation was found to be 25 degrees C, as it was for histamine.

Animals↗
PubMed2000

[Endoscopic transnasal sphenoidal approach in hypophysectomy].

OBJECTIVE: To report the anesthetization and surgical method of transnasal-sphenoidal endoscopic approach in hypophysectomy. METHODS: Forty-two cases with pituitary tumor underwent tranasal-sphenoidal endoscopic surgery and 37 out of 42 accepted local anesthesia and sedation. RESULTS: No complications had occurred, the operations went successfully with less blood loss. Postoperative endoscopic follow-up period was performed at 6 to 35 months. The symptoms were improved in all patients. CONCLUSION: Our results show that transnasal-sphenoidal endoscopic approach under local anesthesia in the treatment of pituitary tumor seems to be a safe simple and valuable way.

Adolescent↗
PubMed2000

[Detection of bcl-2/JH gene rearrangement by semi-nested polymerase chain reaction from fresh tumor samples in patients with laryngeal squamous cell carcinomas].

OBJECTIVE: To evaluate the clinical implications of bcl-2/JH gene rearrangement in laryngeal squamous cell carcinomas (LSCC). METHODS: Bcl-2/JH gene rearrangement analysis in fresh tumor samples was performed in 60 patients with LSCC by semi-nested polymerase chain reaction(PCR). RESULTS: The results showed that bcl-2/JH gene rearrangement was found in 37 out of 60 patients. The breakpoint was located within the major breakpoint region(mbr) in 33 of the 60 patients and the remaining patients had bcl-2 translocation within the minor cluster region(mcr). The results of the study showed that the rearrangement rate of bcl-2 gene was not related to the grade of differentiation, clinical stage, and neck lymph-node metastasis (P > 0.05), and it was related to heavy smoking (P < 0.05). CONCLUSION: Detection of bcl-2/JH gene rearrangement could reveal that bcl-2/JH fusion gene in LSCC is an important molecular biological marker and has a significant role in occurrence and development of LSCC.

Adult↗
PubMed2000

[Staining of complete denture: a preliminary clinical study]

OBJECTIVE:To study the relation between staining of complete denture and drinking tea, coffee and smoking, and to evaluate the result of denture cleaning agent on removing stain of complete denture.METHODS:A survey of 176 patients with complete dentures were carried out, which included the history of drinking tea, coffee and smoking, the use of denture-cleaning agent and the times of daily use. Statistical analysis was performed to determine the relationship between staining of denture and the above factors. RESULTS:The results showed (1)The longer the complete denture was weared, the more serious the staining. (2)Drinking tea and smoking were the main causes for denture staining. (3)Daily use of cleaning agent can effictively remove stain of denture. CONCLUSION:Change of life habit(drinking less tea and stop of smoking) and daily use of cleaning agent can reduce denture staining.

Journal Article↗
PubMed1999

Cloning and characterization of the esp region from a dog attaching and effacing Escherichia coli strain 4221 and detection of EspB protein-binding to HEp-2 cells.

The espA, espB and espD genes from enteropathogenic Escherichia coli were previously shown to be essential for triggering the signal transduction in infected host cells. We have cloned and determined the nucleotide sequences of the espA, espB and espD homologues from an E. coli strain (4221) isolated from a dog which manifested the attaching and effacing lesions in the small intestine. This strain is designated as a dog enteropathogenic E. coli. When comparing predicted amino acid sequences to those of the corresponding proteins from enteropathogenic E. coli O127, enterohemorrhagic E. coli serotype O26, enterohemorrhagic E. coli O157 and rabbit enteropathogenic E. coli, the EspADEPEC protein showed the same level of similarity (75% identity) with EspA of enteropathogenic E. coli O127 and rabbit enteropathogenic E. coli. The EspBDEPEC protein showed the highest similarity with the EspB of enteropathogenic E. coli O127 (99% identity). The EspDDEPEC protein showed 88% identity with the EspDEPEC. We constructed and purified a maltose-binding fusion protein containing the product of the entire espBDEPEC gene of the dog enteropathogenic E. coli strain 4221. Purified maltose-binding protein-EspBDEPEC fusion protein was shown to bind efficiently to HEp-2 cells in a localized fashion as shown by immunofluorescence microscopy. In addition, when the dog enteropathogenic E. coli strain 4221 was grown in tissue culture medium (DMEM) supplemented with serum, a secreted 36-kDa protein was identified by immunoblot analysis using a polyclonal antiserum against the maltose-binding protein-EspBDEPEC fusion protein.

Amino Acid Sequence↗
PubMed1999

Improving high-resolution MR bold venographic imaging using a T1 reducing contrast agent.

Recently, a new imaging method was proposed by Reichenbach et al (Radiology 1997;204:272-277) to image small cerebral venous vessels specifically. This method, referred to as high-resolution blood oxygen level-dependent venography (HRBV), relies on the susceptibility difference between the veins and the brain parenchyma. The resulting phase difference between the vessels and the brain parenchyma leads to signal losses over and above the usual T2* effect. At 1.5 T, a rather long TE (roughly 40 msec) is required for this cancellation to become significant, leading to enhanced susceptibility artifacts and a long data acquisition time. In this study, we examine the utility of incorporating a clinically available T1 reducing contrast agent, Omniscan (Sanofi Winthrop Pharmaceuticals, NY, NY), with the HRBV imaging approach to reduce susceptibility artifacts and imaging time while maintaining the visibility of cerebral veins. Using a double-dose injection of Omniscan, we were able to reduce TE from 40 to 25 msec. This led to a decrease in TR from 57 to 42 msec, allowing a 26% reduction in data acquisition time while maintaining the visibility of cerebral venous vessels and reducing susceptibility artifacts. J. Magn. Reson. Imaging 1999;10:118-123, 1999.

Artifacts↗
PubMed1999

Distribution of a novel locus called Paa (porcine attaching and effacing associated) among enteric Escherichia coli.

Using TnphoA transposon insertion mutagenesis, we found a porcine EPEC (PEPEC) mutant demonstrating as inability to induce AE lesions. The insertion was identified in a gene designated paa (porcine attaching and effacing associated). The distribution of paa in PEPEC O45 strains revealed that it was associated with presence of the eae and its AE phenotype in vivo. On examination of enteric E. coli isolates from humans and various animal species, a strong correlation with the presence of paa was found in EHEC O157:H7 and O26, and dog, rabbit, and pig eae-positive isolates, and to a lesser extent in human EPEC eae-positive isolates. Also, among porcine ETEC isolates, a strong association was found with the presence of LT encoded genes. In contrast, paa sequence was rarely found in enteric E. coli isolates lacking ETEC and AEEC virulence determinants. Thus, our results suggest that Paa could play a role in the AE mechanism and other mechanisms of enteric disease.

Animals↗
PubMed1999

Effects of intrathecal galanin on nociceptive responses in rats with mononeuropathy.

The present study was performed on rats with experimental mononeuropathy induced by left common sciatic nerve loose ligation. Unilateral sciatic nerve loose ligation induced decreases of the hindpaw withdrawal latency to the hot-plate test, cold-plate test and the Randall Selitto test. Sciatic nerve loose ligation induced hyperesponsiveness to touch at room temperature also. Intrathecal administration of either 3 or 6 nmol of galanin, but not 1 nmol, induced significant bilateral increases in hindpaw withdrawal latencies to the hot-plate test, cold-plate test and the Randall Selitto tests in rats with left mononeuropathy. The results indicate that galanin may play important roles in transmission of presumed nociceptive information in the spinal cord of mononeuropathic rats.

Animals↗
PubMed1999

Raman spectroscopic study of changes in fish actomyosin during setting.

Actomyosins (AMs) isolated from tilapia, lemon sole, ling cod, and rock fish were heated at 40 degrees C, and structural changes in AMs were investigated using Raman spectroscopy to elucidate low-temperature gelling phenomenon, that is, "setting", of surimi. The following conformational transitions were observed in lemon sole, ling cod, and rock fish gels during setting: a slow unfolding of alpha-helix and exposure of hydrophobic amino acid residues occurring in long-time incubation at 40 degrees C, thereby forming hydrophobic interactions among AM molecules. In addition, the most frequent conformation in disulfide bonds was gauche-gauche-trans (g-g-t) form in the set gel. On the other hand, tilapia AM did not form a gel with heating at 40 degrees C, its alpha-helical structure in the myosin being far more stable than that of the other species. The heat resistance of the tight alpha-helix may prevent the gelation of tilapia AM. It is, therefore, likely that the unfolding of the alpha-helix of myosin is a prerequisite for gelation of AM during setting.

Actomyosin↗
PubMed1999

TCM treatment with the modified wendan tang in 40 cases of melancholia.

Melancholia is a syndrome caused by emotional stress and stagnation of qi, involving the liver, affecting the heart and spleen, and leading to disharmony of qi of the zang-fu organs. Because of the complicated condition, it is not easy to determine the therapeutic principles. In this series of 40 cases, the modified Wen Dan Tang (Decoction for Clearing Away Gallbladder-Heat) was used for the treatment. Of them, 19 cases were cured, 16 improved, and 5 failed, with total effective rate of 87.5%.

Adult↗
PubMed1999

[Comparative study on osteogenesis of three types growth factors recombination artificial bones].

OBJECTIVE: To compare the osteogenesis of recombination artificial bones, which are bovine deproteined bone (bDPB) and bovine bone morphogenetic protein (bBMP), combined with tumor necrosis factor alpha (TNF alpha), basic fibroblast growth factor (bFGF), epidermal growth factor (EGF) respectively. METHODS: One hundred trephined skull bone defects in fifty rabbits were divided into four groups, which implanted with bDPB/bBMP/TNF alpha, bDPB/bBMP/bFGF, bDPB/bBMP/EGF, and bDPB/bBMP respectively. X-ray and histological changes were observed in the 1st, 2nd, 4th, 6th, 8th weeks after implantation. The content of 35S and 45Ca and ash weight were measured at 10 and 42 days after operation. RESULTS: The osteogenesis of bDPB/bBMP/TNF alpha group was stronger than that of bDPB/bBMP/bFGF group(P < 0.01), while bDPB/bBMP/bFGF group was stronger than that of bDPB/bBMP/EGF(P < 0.01). No significant statistical difference were found between bDPB/bBMP/EGF and bDPB/bBMP(P > 0.05). CONCLUSION: TNF alpha combined with bBMP and carrier can stimulate bone formation and increase the volume of new bone in vivo. It suggests that bDPB/bBMP/TNF alpha is a valuable biomaterial of bone graft.

Animals↗