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Biomedical subjects

X Hu

Publications and source records attributed to X Hu.

At least 415 records · Page 23Linked to original sources
PubMed1995

[Evaluation of segregation ratio and hereditability of esophageal cancer--a comparative epidemiologic study in Huai'an County].

A genetic epidemiologic case-control study including 407 pedigrees (249 cases and 158 controls) was carried out to estimate the segregation ratio and the hereditability (h2) of esophageal cancer by using the method of Li-Mantel-Gart and Falconer, respectively, and to compare the genetic epidemiologic features from the other cancers. The results showed that the segregation ratio of esophageal cancer was 0.1347, significantly less than 0.25 and the genetic model belonged to polygenetics. The h2 of esophageal cancer was 21.41%, 20.23% for female and 13.57% for male. It is concluded that genetic factor is one of the risk factors for esophageal cancer and specially of importance for female, but it is not a main risk factor for esophageal cancer. The results of comparative epidemiologic study among the cancers of lung, stomach, liver and large bowel showed that the segregation ratios of the cancers (except stomach, no data) were all less than 0.25, and the h2 of gastric and liver cancers were higher, which were 52.40% and 51.85%, respectively.

Case-Control Studies↗
PubMed1995

[Transferrin receptor and iron deposition pattern in the hepatic lobules of the iron-deficient and iron-overloaded rats].

Wistar rats were made iron deficient by a low iron regimen. Iron overload was produced by repeated intraperitoneal injections of ferric nitrilotriacetate (Fe(3+)-NTA) for one to four months. Hepatic tissues from these iron deficient, overloaded and control rats were examined for transferrin receptor (TfR), transferrin (Tf) and iron after immunohistochemical staining. TfR and Tf were mainly distributed in the peripheral part of the lobule (zone 1) in the normal, iron deficient and iron-overloaded rats. The staining intensity decreased from zone 1 to zone 3. The staining intensity of TfR was strongest in iron-deficiency rat hepatic cells, weakest in iron-overloaded rat hepatic cells when compared with controls. The difference of Tf staining between the three groups of rats was similar to that of TfR. In the iron-overloaded rats, the staining intensity of iron was stronger in zone 1 than in zone 2 and 3, similar to the distribution pattern of TfR and Tf. These findings suggest that (1) iron uptake in hepatic cells in vivo is regulated and mediated by TfR and Tf, (2) the expression pattern of TfR and Tf in zone 1 to zone 3 liver cells may result in the progressive decrease of iron deposition in the hepatic lobules of the iron overloaded rats.

Anemia, Iron-Deficiency↗
PubMed1995

Functional MR imaging in the evaluation of the patient with epilepsy. Functional localization.

Functional magnetic resonance imaging is able to define noninvasively the location of eloquent cortex responsible for speech, motor, and visual function, and it holds promise for localizing other important functional tissues in the future. Such localization is extremely important to the epileptologist and surgeon planning surgical resection of an epileptic focus. Early work identifies the actual seizure focus using similar techniques. Magnetic resonance, with functional magnetic resonance added to high-resolution magnetic resonance imaging and magnetic resonance spectroscopy, has the potential of providing, in a cost-effective manner with one noninvasive modality, the functional, anatomic, and chemical parameters pertinent to the management of the seizure patient.

Brain↗
PubMed1995

[Analysis of HLA-DRB1 alleles in patients with IDDM].

HLA-DR association with IDDM in local population in Beijing was studied by PCR/SSP typing. The frequency of HLA-DR9 was significantly higher in diabetic patients (30.3% [45/148] vs 17.92% [38/212], chi 2 = 6.97, P < 8.3 x 10(-3)). DR3 was higher in diabetic patients in this study (7.0% [10/148] vs 2.36% [5/212], chi 2 = 3.19, P > 0.05) and DR2 was lower in patients with IDDM (7.4% [11/148] vs 19.8% [42/212], chi 2 = 9.67, P < 1.9 x 10(-3)). These results suggest that DR9 and DR3 both were positively associated with IDDM, but DR2 was negatively associated with IDDM.

Adolescent↗
PubMed1995

[Non-radioactive detection of dinucleotide repeat polymorphisms and its application to genetic diagnosis].

We have developed a rapid and non-radioactive procedure for detecting dinucleotide repeat polymorphisms. Specific primers flanking the repeats were used in the polymerase chain reaction (PCR). The generated allelic fragments were resolved by thin-layer denaturing polyacrylamide gel electrophoresis and visualized by improved silver staining. This method is simple, fast and without labelling of PCR products. Resolution of 1 bp can be easily obtained. It can also be used in multiplex PCR analysis of (CA)n loci. This method will be a valuable tool for linkage analysis and DNA diagnosis as demonstrated by its successful application to the CA dinucleotide repeat haplotying of a DMD family.

Base Sequence↗
PubMed1994

Quantitative analysis of bencynonate in human plasma using a deuterated internal standard by gas chromatography-mass spectrometry with selected-ion monitoring.

A gas chromatographic-mass spectrometric method is described for the quantitative analysis of bencynonate in human plasma. Deuterated bencynonate served as the internal standard and selected-ion monitoring of the fragments of bencynonate and internal standard permitted the quantitation of bencynonate down to 25 pg/ml of plasma. The assay is linear for plasma bencynonate concentrations in the range 25 pg/ml-3 ng/ml. At 0.25 ng/ml the recovery and coefficient of variation are 54.3% and 19.1%, respectively. Application of the method to clinical studies gave data for the pharmacokinetics and relative bioavailability of bencynonate in man.

Animals↗
PubMed1994

The novel behaviour of interactions between Ni2+ ion and human or bovine serum albumin.

We discovered a series of novel behaviours of interactions between Ni2+ ion and human or bovine serum albumin. Our results indicated that there exist two closely neighbouring identical prior binding sites in the binding of human or bovine serum albumin with Ni2+ ions, not only one. It is very likely that, after the binding of the first Ni2+ ion, an induced slow conformational transition happens, which leads to the binding of the second Ni2+ ion and shows itself as a hysteretic effect for a process of non-enzymic protein binding with metal ions. As the concentrations of the 1:1 (molar ratio of Ni2+ ion to protein) system increase, an increasing hypochromic effect is observed. Such a hypochromic effect has not been reported previously; however, it is in accord with the mechanism of dipole-dipole interactions between the electric dipole transition moments of chromophores.

Animals↗
PubMed1994

Cloning and sequencing of the cDNAs encoding two alternative splicing-derived variants of the alpha subunit of the granulocyte-macrophage colony-stimulating factor receptor.

Two distinct cDNA clones, corresponding to alternative mRNA splicing variants of the alpha subunit of the granulocyte-macrophage colony-stimulating factor receptor (GM-CSF-R alpha) were isolated from human blood mononuclear cells by RT-PCR. The first one lacks 179 bp, and the second one lacks 136 bp of the major variant, GM-CSF-R alpha 1. Both of variants result in shifts in the reading frame and are expected to encode 377- and 285-amino-acid membrane anchoring and soluble receptor isoforms, respectively.

Amino Acid Sequence↗
PubMed1994

Investigation of meperidine and its metabolites in urine of an addict by gas chromatography-flame ionization detection and gas chromatography-mass spectrometry.

A gas chromatographic method with flame ionization detection (FID) for the quantitative analysis of meperidine and mass spectrometry (MS) for the qualitative analyses of meperidine and its metabolites in urine was established. Meperidine, normeperidine and acetyl normeperidine in urine were extracted with ether. Free and conjugated meperidinic and normeperidinic acids in urine, which are hydrophillic, were hydrolyzed by acid, esterified with methanol and derivatized with acetic anhydride. Meperidine and its four metabolites were identified by GC-MS. Meperidine was measured by GC-FID during 72 h after intramuscular administration of meperidine to an addict.

Biotransformation↗
PubMed1994

Association of fibroblast growth factor receptor-1 with c-Src correlates with association between c-Src and cortactin.

The initiation of maximal DNA synthesis by fibroblast growth factor (FGF)-1 requires the presence of the growth factor during the entire G0 to G1 transition period of the cell cycle (Zhan, X., Hu, X., Friesel, R., and Maciag, T. (1993) J. Biol. Chem. 268, 9611-9620). During this time, the phosphorylation of several novel proteins on tyrosine residues occurs, and one of these phosphotyrosyl-containing proteins has been characterized as the murine homolog of the chicken cortactin gene (Zhan, X., Hu, X., Hampton, B., Burgess, W.H., Friesel, R., and Maciag, T. (1993) J. Biol. Chem. 268, 24427-24431), a putative substrate for v-Src. We have examined the possibility that FGF-1 employs c-Src or Src-like kinases as signaling intermediates during the mid and late G1 phase of the NIH 3T3 cell cycle using immunoprecipitation and immunoblot analysis. We have demonstrated that c-Src can associate with cortactin in a FGF-1-dependent manner. We have also demonstrated that a monoclonal antibody prepared against FGF receptor (R)-1 is able to co-precipitate Src-related proteins in lysates from FGF-1-treated NIH 3T3 cells. Furthermore, a kinase-active form of FGFR-1 expressed in a bacterial system was also able to associate with Src kinases in a manner dependent on the phosphorylation status of the FGFR-1 protein. Lastly, the Src homology (SH)-2 domain of v-Src was able to recognize a recombinant form of FGFR-1. Because (i) the association between FGFR-1 and Src-like kinases exhibits kinetics similar to those observed between the Src kinases and cortactin and (ii) the Src-SH2 domain is likely to be involved in the association with FGFR-1, we propose that the association of c-Src with activated FGF receptors may be responsible for the tyrosine phosphorylation of cortactin during the mid to late G1 phase of the cell cycle.

3T3 Cells↗
PubMed1994

Synthesis of myristoyl CoA analogues and myristoyl peptides as inhibitors of myristoyl CoA:protein N-myristoyltransferase.

To develop inhibitors of myristoyl CoA:protein N-myristoyltransferase (NMT), a series of myristoyl coenzyme A analogues and myristoyl peptides were synthesized, including S-(2-oxopentadecyl)-CoA (1), S-(2-hydroxypentadecyl)-CoA (2), S-(2-oxopentadecyl)-pantetheine (3), Myr-N-Gly-(L)-Phe (4), Myr-N-Gly-(L)-Tyr (5), and Myr-N-Gly-(L)-Asn-Ala- Ala-Ser-Ala-Arg-(NH2) (6). Biological evaluation of these compounds in an in vitro NMT enzyme assay revealed that the nonhydrolyzable acyl CoA analogue 1 was the most potent inhibitor [inhibitor dissociation constant (Ki) = 24 nM]. A preliminary structure-activity relationship study showed that the adenosine moiety and the 2-keto group in this nonhydrolyzable analogue were necessary for inhibitory activity. A possible mechanism for the inhibition of NMT by 1 was proposed, in which 1 might block the reaction at the stage of an acyl-CoA-NMT-peptide complex. Product analogues such as the myristoylated peptides 4-6 were poor inhibitors of NMT.

Acyl Coenzyme A↗
PubMed1994

Accurate T1 determination from inversion recovery images: application to human brain at 4 Tesla.

It is well known that the signal polarity in inversion-recovery (IR) images changes with inversion time, complicating the determination of T1. To avoid this problem, a simple subtraction method is implemented. In this method, k-space data of the longest inversion time are subtracted from the corresponding data of each inversion time. This subtraction yields IR images of same polarity, making it straightforward to derive T1 using a standard fitting routine. Phantom T1 studies with IR Turbo-FLASH images demonstrate that this technique is robust and accurate. Four Tesla T1 values of the human brain were also determined by this method to demonstrate its in vivo utility.

Brain↗
PubMed1994

Reduction of signal fluctuation in functional MRI using navigator echoes.

Functional magnetic resonance imaging is sensitive to signal fluctuations due to physiological motion and system instability. In this paper, motion-related signal fluctuations are studied, and a method that uses navigator echoes to monitor and compensate for signal fluctuations in a gradient-echo sequence is described. The technique acquires a "navigator" signal before the application of the phase-encoding and readout gradients and corrects the phase of the subsequently acquired imaging data. This technique was implemented on a 4 Tesla whole body system and validated on normal volunteers. With this technique, temporal fluctuations in image intensity were substantially reduced and improved functional activation maps were obtained.

Artifacts↗
PubMed1994

Reduction of field of view for dynamic imaging.

This paper describes a simple technique that improves the temporal resolution for certain dynamic imaging applications. The technique is based on the assumption that the image to image intensity changes sought in dynamic imaging studies are sometimes localized, and a smaller field of view can be used to reduce imaging time. Technical details and experimental results are presented. Experimental results show that this technique works reasonably well for in vivo applications.

Algorithms↗