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Biomedical subjects

X Fan

Publications and source records attributed to X Fan.

At least 127 records · Page 7Linked to original sources

Cloning and expression of Aplysia carboxypeptidase D, a candidate prohormone-processing enzyme.

Many peptide hormones in a variety of species are produced from larger precursors by limited proteolysis at basic amino acid-containing sites. The marine mollusc Aplysia has homologs of mammalian peptide-processing enzymes, including furin, prohormone convertase 1 (PC1), PC2, and carboxypeptidase E (CPE). A novel neuronal Aplysia enzyme was recently identified that was most closely related to carboxypeptidase D (CPD; Fan and Nagle, DNA Cell Biol. 15, 937-945, 1996), a second carboxypeptidase thought to be present in the secretory pathway and to contribute to peptide hormone processing. We have identified and cloned multiple overlapping bag-cell neuron cDNAs that encode two proteins that are members of the CPD family. Sequence analyses demonstrate that the longer CPD protein (1446 residues) contains an N-terminal signal peptide and four carboxypeptidase-like domains; the third and fourth domains are not predicted to form active enzymes, as several critical residues are absent. The shorter CPD protein is predicted to contain two active carboxypeptidase-like domains. Northern blot analysis identified a major Aplysia CPD mRNA (5.3 kb) and several smaller minor transcripts in central nervous system tissue. The CPD was purified from Aplysia ovotestis using a method previously developed for mammalian CPD. The purified Aplysia CPD binds antisera raised against regions of the protein encoded by the Aplysia cDNA clone, as well as an antiserum raised against duck CPD. The enzymatic properties of purified Aplysia CPD are generally similar to those of mammalian CPD. Aplysia CPD is a candidate prohormone-processing enzyme that may play a role in the processing of Aplysia prohormones in the secretory pathway.

Amino Acid Sequence↗

Comparison of genetic heterogeneity of hepatitis C viral RNA in liver tissue and serum.

OBJECTIVE: Hepatitis C virus (HCV) is known to be heterogeneous and to circulate as a group of closely related quasispecies in individual patients, although hepatic viral genetic characteristics have not been well documented. METHODS: Matched serum and liver samples were tested by reverse transcription polymerase chain reaction amplification and single stranded conformation polymorphism analysis of the hypervariable portion of the E2/NS1 region of the HCV genome. The number of quasispecies was compared with the amount of HCV RNA, HCV genotyping, and infection with the hepatitis G virus. RESULTS: Sixteen of 40 patients had HCV RNA detectable in serum and liver. The HCV genotype was identical in serum and liver of all but one case. HCV RNA levels were approximately 10-fold higher in liver than serum. The number of HCV quasispecies in serum ranged between two and six (median 3.0) and in the liver between 2 and 19 (median 3.5, mean liver/serum ratio 1 to 6.3, median 1.8). The number of quasispecies in liver was equal to or greater than that in serum in all cases. HGV infection was found in 14 cases and did not influence serum or hepatic levels of HCV RNA. CONCLUSIONS: The number of hepatic HCV quasispecies usually exceeds that in serum, independent of the amount of HCV RNA and HCV genotype. This finding is compatible with clearance of some quasispecies from serum, but not liver, by putative neutralizing antibodies.

Adult↗

Experimental assessment of power and temperature penetration depth control with a dual frequency ultrasonic system.

A novel ultrasound applicator for superficial simultaneous thermoradiotherapy consisting of two parallel-opposed linear arrays and a double-sided scanning reflector was constructed and tested for penetration depth control. In this design the arrays operate at different frequencies (1 and 5 MHz, in this study) and the input power to each array element (five 2 X 2 cm2 elements per array) is computer adjustable. The ultrasonic beams from the arrays are aimed at the scanning reflector which in turn deflects them simultaneously and in parallel toward the treatment volume. Relative intensity distributions generated by the prototype were measured in a degassed water phantom using a thermal technique for a selected reflector position; these showed that the ultrasonic intensity distribution can be controlled in the lateral dimensions by varying the input power level to individual array elements. A fixed-perfused canine kidney phantom was employed to demonstrate experimentally that real time penetration depth control is possible by varying the excitation magnitude of one array (frequency) relative to that of the other. It is concluded that the dual-frequency scanned-reflected ultrasound applicator offers a degree of dynamic three-dimensional control of the power deposition pattern of clinical significance.

Animals↗

Existing antilisterial immunity does not inhibit the development of a Listeria monocytogenes-specific primary cytotoxic T-lymphocyte response.

Infection of BALB/c mice with Listeria monocytogenes stimulates an antilisterial immune response evident by the appearance of H2-Kd-restricted CD8(+) cytotoxic T lymphocytes (CTLs) specific for the nanomer peptides amino acids (aa) 91 to 99 of listeriolysin O (LLO 91-99) and aa 217 to 225 of the p60 molecule (p60 217-225). We have introduced point mutations at anchor residues within LLO 91-99 (92F) or p60 217-225 (218F), and BALB/c mice infected with L. monocytogenes strains containing these point mutations do not develop CTLs specific for LLO 91-99 or p60 217-225, respectively. We have used these strains to test whether primary CTL responses against L. monocytogenes-derived determinants can be stimulated within an environment of existing antilisterial immunity. We found that the development of a primary L. monocytogenes-specific CTL response is not altered by existing immunity to L. monocytogenes. For example, primary immunization with the p60 218F strain of L. monocytogenes followed by a secondary immunization with wild-type L. monocytogenes results in stimulation of p60 217-225-specific CTLs at primary response levels and LLO 91-99-specific effectors at levels consistent with a memory CTL response. Similarly, primary immunization with the 92F strain of L. monocytogenes followed by a secondary immunization with wild-type L. monocytogenes results in stimulation of LLO 91-99-specific CTLs at primary response levels and p60 217-225-specific effectors at levels consistent with a memory CTL response. These results provide additional support for the use of L. monocytogenes as a recombinant vaccine vector and show that antivector immunity does not inhibit the development of a primary CTL response when the epitope is delivered by L. monocytogenes as the vaccine strain.

Amino Acid Substitution↗

Structures in Bacillus subtilis are recognized by CD14 in a lipopolysaccharide binding protein-dependent reaction.

The CD14 molecule expressed on monocytes and macrophages is a high-affinity receptor for bacterial lipopolysaccharide (LPS) and hence an important component of the innate immune system. LPS binding protein (LBP) is required to facilitate the binding of LPS to CD14 in vitro and is necessary for the induction of an inflammatory response to LPS in vivo. Here we show that CD14 and LBP can also bind to lipoteichoic acid from the gram-positive bacterium Bacillus subtilis. Although CD14 does not interact with intact B. subtilis organisms, a brief exposure of the bacteria to serum converts them into a form which can bind to CD14 in an LBP-dependent reaction. When serum-pretreated B. subtilis organisms are incubated with the myelomonocytic cell line U937, which expresses CD14, the bacteria are rapidly phagocytosed. The phagocytosis is strictly dependent both on LBP and on CD14. These in vitro results suggest that LBP plays a role in the innate response not only to gram-negative but also to gram-positive infections.

Acute-Phase Proteins↗

Lymphoguanylin: cloning and characterization of a unique member of the guanylin peptide family.

Guanylin and uroguanylin are small peptides containing two disulfide bonds that activate membrane guanylate cyclase-receptors in the intestine, kidney and other epithelia. Hybridization assays with a uroguanylin complementary DNA (cDNA) detected uroguanylin-like messenger RNAs (mRNAs) in the opossum spleen and testis, but these transcripts are larger than uroguanylin mRNAs. RT of RNA from spleen to produce cDNAs for amplification in the PCR followed by cloning and sequencing revealed a novel lymphoid-derived cDNA containing an open reading frame encoding a 109-amino acid polypeptide. This protein shares 84% and 40% of its residues with preprouroguanylin and preproguanylin, respectively. A 15-amino acid, uroguanylin-like peptide occurs at the COOH-terminus of the precursor polypeptide. However, this peptide is unique in having only three cysteine residues. We named the gene and its peptide product lymphoguanylin because the source of the first cDNA isolated was spleen and its mRNA is expressed in all of the lymphoid tissues tested. A 15-amino acid form of lymphoguanylin containing a single disulfide bond was synthesized that activates the guanylate cyclase receptors of human T84 intestinal and opossum kidney (OK) cells, although with less potency than uroguanylin and guanylin. Northern and/or RT-PCR assays detected lymphoguanylin mRNA transcripts in many tissues and organs of opossums, including those within the lymphoid/immune, cardiovascular/renal, reproductive, and central nervous organ systems. Lymphoguanylin joins guanylin and uroguanylin in a growing family of peptide agonists that activate transmembrane guanylate cyclase receptors, thus influencing target cell function via the intracellular second messenger, cGMP.

Amino Acid Sequence↗

A study of early pregnancy factor activity in the sera of women with trophoblastic tumor.

PROBLEM: To detect whether or not the early pregnancy factor (EPF)-like activity, or chaperonin 10, could be in the sera of patients with trophoblastic tumor in order to find another more efficient means to diagnose this kind of tumor. METHOD OF STUDY: The rosette inhibition assay was used to detect EPF-like activity in 216 sera, collected from patients with gestational trophoblastic tumor, including 47 sera of patients with choriocarcinoma, 68 sera of patients bearing invasive mole, and 101 sera of patients with vesicular mole. RESULTS: The accuracy of diagnosing malignant trophoblastic tumor by detecting EPF-like activity is 91.3% (105/115), with a false positive rate of 14.58% and a false negative rate of 4.8% by this method. Furthermore, the rosette inhibition titer (RIT) values have significant difference (P < 0.001) between the sera in patients with malignant trophoblastic tumor before treatment and those after treatment. CONCLUSIONS: This study demonstrated that diagnosis of malignant trophoblastic tumor could be made with an accuracy of 91.3% by detecting EPF-like activity and that EPF-like activity could be used as an indicator to distinguish benign from malignant trophoblastic tumor.

Adult↗

Is hepatitis G/GB virus-C virus hepatotropic? Detection of hepatitis G/GB virus-C viral RNA in liver and serum.

The recently identified hepatitis G virus (HGV, also named GB virus-C, GBV-C) appears to have similarities to hepatitis C virus and other flaviviridae. To better understand its clinical significance and hepatotropism, we collected liver tissue and matched serum samples from 56 patients undergoing liver transplantation. HGV/GBV-C RNA was detected by reverse transcription-nested PCR, using primers from the relatively conserved 5' noncoding region of the genome to detect HGV/GBV-C RNA and the amount was semiquantitatively estimated by serial 10-fold endpoint dilution. The presence and amount of HCV RNA was estimated by the same methodology. Seventeen patients (30%) had HGV/GBV-C RNA detectable either in liver or in serum, including two of three with cryptogenic liver disease. Interestingly, 5 of 17 (29%) patients had HGV/GBV-C RNA in serum but not liver, even with repeated testing of hepatic RNA from different portions of the liver. Furthermore, the titer of HGV/GBV-C RNA was significantly lower in liver than in serum in most samples (mean log titer, 1.33 vs. 2.56, P < 0.05). In contrast, all 21 patients with HCV RNA in serum also had the virus detectable in liver. In five patients coinfected with HCV and HGV/GBV-C, the mean titer of HCV RNA in liver was higher than that in serum (log titer, 2.8 vs. 3.0, P > 0.05). Thus, our results suggest that HGV/GBV-C is probably not hepatotropic and may replicate predominantly in sites other than the liver. These findings brings into question the role of HGV in causing significant liver disease.

5' Untranslated Regions↗

Telephone adaptation of the Modified Mini-Mental State Exam (3MS). The Cache County Study.

OBJECTIVE: To examine the concurrent validity of a newly developed telephone adaptation of the Modified Mini-Mental State Exam. BACKGROUND: Longitudinal studies of cognition may be advantaged by availability of assessment instruments that can be used over the telephone, as well as in person. METHOD: Subjects were 263 noninstitutionalized elderly residents of a rural community in southern Idaho, aged 65 to 93, who had little or no cognitive difficulty. At an average interval of four weeks, we administered the Modified Mini-Mental State Exam (3MS) and the newly adapted Telephone Modified Mini-Mental State Exam (T3MS). Order of administration was randomly assigned. RESULTS: Agreement between scores on the two instruments was good (r = 0.82, p < 0.001). When we applied various cutoff scores to the instruments, thereby generating assignments of individuals to "screen positive" and "screen negative" groups, the percent agreement in screening results ranged from 80% to 96% as we reduced the cutoff scores from 90 to 74 (100 points possible). CONCLUSIONS: At least among subjects without major cognitive syndromes, the Telephone Modified Mini-Mental State Exam provides a reasonable substitute for the more costly in-person 3MS. The telephone instrument should now be tested over a broader range of cognitive abilities in order to assess its validity in more impaired subjects, e.g., by studying an institutionalized sample.

Aged↗

Insecticidal activity of transgenic tobacco plants expressing both Bt and CpTI genes on cotton bollworm (Helicoverpa armigera).

Transgenic tobacco plants expressing both Bacillus thuringiensis (Bt) insecticidal protein and cowpea trypsin inhibitor (CpTI) genes was used to evaluate the insecticidal activity on the cotton bollworm (Helicoverpa armigera) compared with transgenic tobacco with Bt insecticidal protein gene alone. Mortality of first to third instar larvae fed on transgenic two genes tobacco for three days was significantly higher than that fed on transgenic Bt tobacco. First to fourth instar larvae fed on transgenic two genes tobacco continuously could not survive until pupation. Second instar larvae were fed on transgenic tobacco plants for three days and then were transferred to an artificial diet. The efficacy of transgenic two genes tobacco on mortality, larvae weight, percentage of pupation, and time to pupation were significantly higher than that of transgenic tobacco with Bt insecticidal protein gene alone. The results with transgenic tobacco as model plant were valuable for other crops both for the enhancement of insecticidal efficacy and for the delay of insect adaptation to transgenic Bt crops.

Animals↗

[The efficacy of p16, p53 and p21 genes on the proliferation of lung cancer cells in vitro].

OBJECTIVE: Whether the p16, p21 and p53 genes inhibit the proliferation of lung cancer cells after transfecting the genes alone or jointly was examined. METHODS: The p16, p21 and p53 genes mediated by Stearylamine/DOPE (SA liposome) were introduced alone and jointly into the non-small cell lung cancer (NSCLC) cell line A549 and small cell lung cancer (SCLC) SH77. The effect of the genes on the growth of the cells was detected by MTT method at day 1, 3, 5 after gene transfection. RESULTS: The p16, p53 and p21 genes alone mediated by SA liposome can inhibit obviously the growth of NSCLC cell line A549 cells, while the genes were slightly effective on SCLC cell line SH77 cells at day 1, 3, 5 after transfecting the genes. But co-transfecting p16 and p21 or p16 and p53 can enhance the inhibiting effect on both A549 and SH77 cells significantly. CONCLUSIONS: The tumor suppressor genes p16, p53 genes and CDK inhibitor p21 gene may be candidate for gene replacement therapy of NSCLC. Co-transfecting p16 gene and p53 gene may be a better choice.

Carcinoma, Non-Small-Cell Lung↗

[Posttraumatic or inflammatory acute respiratory distress syndrome on high altitude area: a retrospective analysis of 94 deaths due to ARDS/MOF].

OBJECTIVE: To determine the characteristic predictors of acute respiratory distress syndrome (ARDS) in the high altitude area of China. METHODS: According to the diagnostic criteria of ARDS, 2 325 cases were screened in the recent 10 years. Except malignant tumors, cardio-cerebrovascular diseases, chronic obstructive pulmonary disease, and chronic multiple organ failure, the causes of death were analysed retrospectively. RESULTS: 94 cases (4.04%) were diagnosed as ARDS, but in the primary case record, only 27 cases (1.16%) had been diagnosed as ARDS/MOF. Of the 94 ARDS patients, 79 complicated by extrapulmonary organ damage involving the kidney, heart, liver, gastro-intestinal tract, and brain. A total of 305 organs were involved (average 3.24 organs each case). Lung failure only accounted for 15 cases. CONCLUSIONS: The combination of the diagnostic criteria of ARDS for high altitude area and flate area, injury severity scale, blood gas monitoring, and integrated traditional Chinese medicine and western medicine may improve the prognosis of ARDS.

Adolescent↗

[Determination of TNF-alpha and endotoxemia in patients with chronic liver diseases].

The incidence of endotoxemia in 153 patients with different liver diseases was determined by Limulus Lysaite Test(LLT). Comparative studies were carried out on the levels of tumour necrosis factor-alpha(TNF-alpha) between positive and negative endotoxemia in patients suffering from chronic liver diseases. At the same time, 58 patients of positive endotoxemia were divided into two groups--bifidobiogen group (38 cases) and control group(20 cases). The patients in bifidobiogen group were treated mainly with daily administration of bifidobiogen for 1 month besides general liver--protection therapy and the bifidobiogen was not given to the control group. The results showed that: 1. Incidence of endotoxemia in 153 patients suffering from various types of liver diseases was 65.36%; the highest rate was found in the patients with severe hepatitis; 2. The TNF-alpha level was obviously increased in the patients of positive endotoxemia; 3. The total efficacy in bifidobiogen group was significantly higher than that in control group. The data suggest that chronic liver diseases are generally complicated with endotoxemia, and TNF-alpha plays an important role in the pathogenesis of endotoxemia. The serum endotoxin level may be reduced after the treatment with bifidobiogen.

Adult↗

[Investigation on acute stroke patients being admitted to hospital].

One hundred and twelve patients with acute stroke were studied. The results revealed that about 42 percent of 112 patients could get to hospital within 6 hours after onset, in which included 60.4 percent of the hemorrhagic group and 28.1 percent of the infarction group. Comparatively, among 30.3 percent of 112 patients CT scan was carried out within 6 hours, which included 41.7 percent of the hemorrhagic group and 21.8 percent of the infarction group. Linear correlation analysis was studied between admission time(AT) and the assessment of neural function defect(ANFD). The results showed that there was significant negative correlation between AT and ANFD in stroke patients. After analysing the serial reasons of delaying hospitalization, the authors have found that the key factor is the ignorance of the importance of stroke in early stage.

Cerebral Hemorrhage↗

[A study on porins of Escherichia coli HX88108].

To investigate the relationship between porins deficiency and the resistance of Escherichia coli HX88108. The porins of Escherichia coli HX88108 were studied by SDS-PAGE and were compared with the porins of standard strains. The result showed that E. coli HX88108 did not lose OmpF and OmpC, and the molecular weights of these two porins were 38 kd and 37 kd respectively. There is no relationship between the resistance of Escherichia coli HX88108 and porins deficiency.

Drug Resistance, Bacterial↗

[Sub-cloning and preliminary sequence analysis of the gene encoding of a cefoperazone hydrolyzing beta-lactamase isolated from Escherichia coli].

Escherichia coli HX88108, which is resistant to cefoperazone(CPZ), was isolated from a severely infected patient. We studied genetical basis of beta-lactamase produced in E. coli HX88108 by pFL25, one of the recombinant plasmid of pFC. Largescale pFL25 plasmid was extracted, purified, and cleaved with restriction endonuclease EcoR I, Sal I, Pvu I, then subcloned into vector pUC19 as 1.9 kb, 0.9 kb, 0.65 kb fragments respectively. Recomminant plasmids were selected by alpha-complementation and determined by restriction endonuclease analysis. DNA sequencing was performed by the dideoxy polymerase chain termination method. Partial nucleotide sequence(1-78 nucleotide position) of the gene was found to be highly homologous (97%) with the gene coding for TEM-52 extended spectrum beta-lactamase of K. pneumonise, suggesting that the beta-lactamase coded by the cefoperazone resistant gene might be derived from TEM-type beta-lactamase.

Anti-Bacterial Agents↗

[Endoscopic pituitary tumor surgery by nasal cavity and sphenoid sinus].

OBJECTIVE: For reducing surgical trauma to patients of pituitary tumor. METHOD: 12 patients of pituitary tumor were treated with endoscopy by nasal cavity and sphenoid sinus under general anaesthesia. RESULT: Except one died of bleeding within cranial cavity after operation, the rest recovered smoothly without severe complications. During 7 months to one and half year follwing-up, the function of endocrine in 9 cases resumed to normal and 8 of their vision improved to some extent. CONCLUSION: The good illumination and clear visual field under endoscopy could improve the accuracy and security of operation and minimize the injury to normal tissue. But for large or recurrent tumors, this approach should be selected carfully.

Adult↗