Biomedical subjects

A Jiang

Publications and source records attributed to A Jiang.

9 recordsLinked to original sources

PubMed1998

Expression of a p53 mutant in the epidermis of transgenic mice accelerates chemical carcinogenesis.

To develop an in vivo model for studying the role of the p53 tumor suppressor in skin carcinogenesis, a murine p53(172H) mutant (equivalent to human p53(175H)) was expressed in the epidermis of transgenic mice, utilizing a targeting vector based on the human keratin 1 gene (HK1.p53m). HK1.p53m mice developed normally and did not exhibit an obvious epidermal phenotype or develop spontaneous tumors. However, these mice demonstrated an increased susceptibility to a two-stage chemical carcinogenesis protocol, with the rate of formation and number of papillomas being dramatically increased as compared to non-transgenic controls. The majority of papillomas in control mice regressed after termination of 12-O-tetradecanoylphorbol-13-acetate (TPA) treatment, whereas p53m papillomas progressed to carcinomas and metastases. In addition, more advanced malignancy, i.e., undifferentiated spindle cell carcinomas, were exclusively observed in p53m mice. Increased bromodeoxyuridine (BrdU) labeling, accompanied by decreased expression of p21, was observed in HK1.p53m papillomas. In situ examination of centrosomes in HK1.p53m papillomas also revealed marked abnormalities, with 75% of the cells containing > or = 3 centrosomes/cell, whereas centrosome numbers in papillomas from control animals remained normal. These data suggest that the accelerated tumorigenesis observed in chemically-treated p53m mice is most likely due to increased genomic instability resulting from an inhibition of G1 arrest and abnormal amplification of centrosomes.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1997

Expression of a dominant-negative type II transforming growth factor beta (TGF-beta) receptor in the epidermis of transgenic mice blocks TGF-beta-mediated growth inhibition.

To determine whether a functional type II receptor of transforming growth factor beta (TGF-beta) is required to mediate the growth inhibitory effect of TGF-beta on the skin in vivo, we have generated transgenic mice that overexpress a dominant negative-type II TGF-beta receptor (delta beta RII) in the epidermis. The delta beta RII mice exhibited a thickened and wrinkled skin, and histologically the epidermis was markedly hyperplastic and hyperkeratotic. In vivo labeling with BrdUrd showed a 2.5-fold increase in the labeling index over controls, with labeled nuclei occurring in both basal and suprabasal cells of transgenic epidermis. In heterozygotes, this skin phenotype gradually diminished, and by 10-14 days after birth the transgenic mice were indistinguishable from their normal siblings. However, when F1 mice were mated to homozygosity, perinatal lethality occurred due to the severe hyperkeratotic phenotype, which restricted movement. Cultured primary keratinocytes from delta beta RII mice also exhibited an increased rate of growth in comparison with nontransgenic controls, and were resistant to TGF-beta-induced growth inhibition. These data document the role of the type II TGF-beta receptor in mediating TGF-beta-induced growth inhibition of the epidermis in vivo and in maintenance of epidermal homeostasis.

Amino Acid Sequence↗

PubMed1997

[Plasmid DNA fragments from Halobacterium halobium active as eubacteria promoters in Escherichia coli].

In this paper; a promoter-probe plasmid pKK232-8 was used as a vector which functioned in E. coli. The plasmid pHH205 of Halobacterium halobium J7 was digested by two groups of restriction endonucleases BamHI-SalI and HindIII -SalI, recombined in vitro and transformed into E. coli. The transformants were selected on resistance plates to contain ampicillin (Am) and chloramphenicol (Cm). From random-selected 20 strains of transformants we obtained transformants T1 and T2, whose level of Cm resistance got to 110 micrograms/ml. The recombinant plasmids from T1 and T2 were named pJH and pJB, respectively. The resultes of analysis by restriction endonucleases digestion and molecular hybridization showed that recombinant plasmid pJH carried a inserted fragment with size of 800bp from plasmid pHH205. Experimental results of retransfomation proved further that the DNA fragment had promoter function in E. coli. Thus, this indicated that DNA fragments from plasmid of archaebaeteria (H halobium) may function as eubacteria (E. coil) promoters.

Escherichia coli↗

PubMed1996

Molecular mimicry between an immunodominant amino acid motif on the 47-kDa lipoprotein of Treponema pallidum (Tpp47) and multiple repeats of analogous sequences in fibronectin.

Molecular mimicry, resulting from structural similarities between self-determinants on host Ags and an organism's antigenic determinants (epitopes), can incite autoimmune events in certain bacterial and viral diseases. In the course of comprehensively mapping the 47-kDa lipoprotein (Tpp47) of Treponema pallidum subsp. pallidum using an overlapping synthetic peptide strategy, we identified a major immunoreactive epitope (411PGTEYT416) that exhibited considerable motif identity with multiple repeats of analogous linear sequences found in mammalian fibronectins. To further explore the importance of this motif as a probable instigator in the induction of polyspecific cross-reactive Abs, mimetic variants were synthesized for immunologic studies. Mimetics with ala (A) replacements in each amino acid position were used to determine which residues were critical for Ab binding. Animals immunized with two mimetics (PGTEYT or PGSEYT) coupled to tetanus toxoid exhibited: 1) modified responses when challenged with viable T. pallidum; and 2) classical Arthus reactions when challenged intradermally with either motif linked to a different carrier. The cross-reactive nature of the Ab responses to both mimetics was confirmed in a variety of ELISAs using mimetics, fibronectins, and collagens. Inhibition-ELISA studies with both fibronectin and an unrelated mimetic of the RGD motif suggest that intra- and intermolecular epitope spreading occurs following mimetic immunization and involves additional self-epitopes. These observations suggest that although molecular mimicry plays a pivotal role in initially triggering the anti-fibronectin and anti-collagen responses associated with disseminated syphilis, expansion of those autoimmune responses may be due to other self-epitopes once tolerance is abrogated.

Amino Acid Sequence↗

PubMed1996

Functional magnetic resonance imaging of symptom provocation in obsessive-compulsive disorder.

BACKGROUND: The new technique of functional magnetic resonance imaging was used to investigate the mediating neuroanatomy of obsessive-compulsive disorder symptoms. METHODS: Ten patients with obsessive-compulsive disorder and 5 normal subjects were studied via functional magnetic resonance imaging during control and provoked conditions. Data analysis entailed parametric and nonparametric statistical mapping. RESULTS: Statistical maps (nonparametric; P < 10(-3)) showed activation for 70% or more of patients with obsessive-compulsive disorder in medial orbitofrontal, lateral frontal, anterior temporal, anterior cingulate, and insular cortex, as well as caudate, lenticulate, and amygdala. No normal subjects exhibited activation in any brain region. CONCLUSIONS: Results of functional magnetic resonance imaging were consistent with past studies of obsessive-compulsive disorder that used other functional neuroimaging modalities. However, paralimbic and limbic activations were more prominent in the present study.

Adult↗

PubMed1996

Automatic motion correction for breast MR imaging.

In 29 gadolinium-enhanced breast magnetic resonance (MR) examinations, breast motion prevented accurate and efficient image processing. To compensate for global rotations and translations, an automatic motion correction method with a ratio-variance minimization algorithm was used to align images at multiple time points through an iterative process. This method reduced breast motion and improved the accuracy and efficiency of lesion detection.

Adult↗

PubMed1996

[Dynamic change of beta 2-microglobulin in hemodialysis].

In order to study the dynamic clearance of total beta 2-microglobulin in the body, two-compartment theory and perturbation solution were applied in our study. Based on the rate of formation of beta 2-microglobulin in the body and the mode of transmission and mass transfer resistance of solute, the concept of week clearance index of beta 2-microglobulin (R value) was suggested. Its theoretical value is more than 40%. Thirty-two patients undergoing dialysis with high-efficiency dialyzer were studied and data were processed in a computer. The results showed that when R value was more than 40%, the clinical manifestation of amyloidosis carpal tunnel syndrome induced by increase of beta 2-microglobulin was alleviated obviously. It makes up for the limitation of KT/V or TA Curea that were used only to estimate adequate dialysis of small molecules. It is shown that the concept of week cleacance index of beta 2-microglobulin improves the estimation of adequate dialysis.

Adult↗

PubMed1995

[Occurrence of renal cyst and tumor in patients under longterm hemodialysis].

In a period of 12 years, 887 renal failure patients were treated with hemodialysis in our research center. In 512 patients (57.7%) renal cysts were detected by ultrasonagraphy and/or CT. The cysts were apparently acquired during hemodialysis rather than congenital. More important is the fact that in 19 patients with renal cysts tumor subsequently developed. Surgical specimen confirmed that the tumor was malignant in 8 and benign in 11. The mechanism of genesis of renal cyst and tumor in patients under longterm hemodialysis is discussed. The failed kidneys become ischemic and fibrotic and the glomeruli are functionless or completely replaced by fibrotic tissue. Under the situation, the decreased washing-out effect of urinary flow in the renal tubules and tubular obstruction most likely account for cyst formation. The constant chemical and/or physical irritation by the cyst contents combined with the longterm uremia-induced immuno-suppression may contribute to the neoplastic transformation. From the sequence of events, renal cyst may be considered as a pre-cancerous manisfestation.

Adolescent↗

PubMed1994

Analysis of therapeutic effects of acupuncture on abstinence from smoking.

1. Similar to other methods for abstinence from smoking, the acupuncture means has the same problems, i.e., recurrence, gradual decrease of therapeutic effects as the time goes on and unstable immediate effects. Therefore, any researches without a follow-up study are of little clinical significance. 2. Gilbey V et al pointed out that, up to now, the abstinence rates of all the methods have fluctuated between 20.0% to 35.0%, and the effective rates are around 45.0%; this is close to the average long-term effects reported in this paper. 3. Quite a number of researchers have pointed out that acupuncture is effective for many smokers who have failed to quit smoking by other methods. Research results have also indicated that the therapeutic effects of acupuncture on abstinence from smoking are similar to that of the nicotine chewing gum method and the behaviour therapy, suggesting that acupuncture is neither superior nor inferior to other methods in stopping smoking, and actually these methods can complement each other. 4. Schwartz pointed out that, the methods used in the past to quit smoking were difficult to be accepted by the majority of smokers, resulting in unsatisfactory therapeutic effects. In general, acupuncture is painless, nontraumatic, without untoward reactions, being able to inhibit the abstinence syndrome, economic, simple, etc. and eventually it is easy to be accepted by smokers. Therefore, if other methods are unsatisfactory, the acupuncture method can be tried.

Acupuncture Points↗