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Biomedical subjects

D Shi

Publications and source records attributed to D Shi.

At least 37 records · Page 2Linked to original sources
PubMed2001

[Clinicopathological and molecular genetic analysis in Chinese typical hereditary nonpolyposis colorectal cancer pedigrees].

OBJECTIVE: To investigate the clinicopathological and molecular genetic characteristics of Chinese hereditary nonpolyposis colorectal cancer (HNPCC) pedigrees. METHODS: Four Chinese HNPCC pedigrees were studied using microdissection, microsatellite instability analysis, immunohistochemistry staining and direct DNA sequencing for hMSH2 and hMLH1 genes. RESULTS: All five tumor tissues from 4 probands showed high level of microsatellite instability at more than 2 loci(RER + phenotype). Three of 4 cases lost hMSH2 protein expression and one case showed no hMLH1 protein expression. Three pathological germline mutations (2 on hMSH2 and 1 on hMLH1) were identified. CONCLUSIONS: Chinese typical HNPCC kindreds showed relatively frequent germline mutations of mismatch repair genes. Microsatellite instability analysis and immunohistochemistry staining might be the effective screening methods before direct DNA sequencing for the detection of mismatch repair genes. It is necessary to establish clinical criteria and molecular diagnostic strategies more suitable for Chinese HNPCC kindreds.

Adult↗
PubMed2001

[MRI diagnosis of painful ophthalmoplegia syndrome].

OBJECTIVE: To study MRI appearances of painful ophthalmoplegia syndrome and provide image basis for clinical diagnosis of painful ophthalmoplegia syndrome. METHODS: Seventeen cases with painful ophthalmoplegia syndrome diagnosed clinically were collected. MRI ordinary scan and gadolinium-diethylene triamine pentaacetic acid (Gd-DTPA) contrast fatty-restraint scan were performed on the orbit and cavernous sinus. RESULTS: MRI appearances of painful ophthalmoplegia syndrome included patch or small nodule abnormal signal at the region of fissura orbitalis superior. The ipsilateral cavernous sinus was enlarged. The local lobus temporalis meninges close to the fissura orbitalis superior and cavernous sinus were invaded. MRI contrast fatty-restraint scan might clearly show the pathological changes. CONCLUSION: MRI may provide image basis for the clinical diagnosis of painful ophthalmoplegia syndrome.

Adult↗
PubMed2001

[Mutations of APC and K-ras gene in aberrant crypt foci from human colon].

OBJECTIVE: To analyze the mutations of K-ras and APC gene in normal colorectal mucosa, aberrant crypt foci (ACF), adenoma and colorectal carcinoma (CRC); To study the genetic alteration in ACF and its possibility of being a molecular marker of very early colon cancer and to explore the relationship of ACF and colorectal adenoma. METHODS: DNA from 35 CRC, 15 adenomas, 34 ACF and 15 cases of normal mucosa with mucous glands were isolated by micro-dissection. Direct gene sequencing of k-ras gene including codon 12, 13 and 61 as well as the mutation cluster region (MCR) of APC gene. RESULTS: Mutation frequency of k-ras gene in ACF, adenoma and carcinoma was 17.6% (6/34), 13.3% (2/15), and 14.3% (5/35) respectively, showing no difference between the three pathologic changes. The ras gene mutation sites in adenomas, carcinomas and 4 ACF were limited to codon 12 (GGT-->GAT), but in 2 ACF, they were located in codon 13 (GGC-->GAC). K-ras gene mutation in ACF was found more frequently in old patients and in patients with polypoid cancers. No mutations were found in codon 61 in three types of tissue. Mutation rate of APC genes in adenomas and carcinomas was 22.9% (8/35) and 26.7% (4/15) respectively, which was higher than that of ACF 2.9%, (P < 0.05). APC gene mutation in carcinomas was not correlated with age, location, size and differentiation. CONCLUSION: The morphological changes and gene mutation status are different in ACF and adenomas. ACF is a very early morphological lesion in the carcinogenesis of colorectal carcinoma. Therefore, ACF is considered to be the putative "microadenoma" where the development of colorectal carcinomas may be from "normal epithelium to ACF and then to carcinomas".

Adenoma↗
PubMed2001

[Pathogen detection in the myocardial lesion using in situ RT-PCR in mice induced by experimental CoxB(3m) virus infection].

OBJECTIVE: To detect the location of pathogens in myocardium using in situ RT-PCR technique in order to study the pathogenetic course of the myocardial lesion induced by CoxB(3m) virus infection in mice. METHODS: (1) Thirty and fifty Balb/c mice were used respectively to establish the acute and chronic CoxB(3m) infected models, with another 25 healthy mice as the controls; (2) KS400 image analysis system (Germany) was used to measure the cardiac chamber area and the left ventricular wall thickness of the chronic infected mice and the controls; (3) CoxB(3m) virus in myocardial tissue was detected using in situ RT-PCR by direct incorporated technique which employed nucleotide labeling by anti-digoxin antibody and bonded with alkaline phosphatase (anti-dig-AKP method). RESULTS: Picture analysis indicated that the left ventricular chamber area was enlarged and the left ventricular wall was thinner in the chronic repeated virus infected models than those of the controls. With in situ RT-PCR, positive signals for Coxsackie virus B(3m) RNA were detected not only in the myocardium of the acute Balb/c mice models but also in the myocardium of the chronic mice models. CONCLUSION: Coxsackie virus B(3m) is able to induce pathologic lesions by exhibiting positive CVB-RNA signals in both acute and chronic models in mice. In the chronic experimental models, the cardiac chamber is enlarged while the ventricular wall is thinned which demonstrates the association with persistent infection of Coxsackie virus B(3m) virus.

Animals↗
PubMed2001

[Mössbauer spectroscopy and its application in the study of iron cation behavior in molten slags].

The principle, parameters and determination methods of Mössbauer spectroscopy are summarized. The iron cation behavior in molten slags is analyzed and Mössbauer spectra characteristics of Fe2+, Fetet3+ and Feoct3+ ions are detailed chemically and spetroscopically. The relationship between iron cation behavior and basicity, total iron, Na2O and Al2O3 addition in slags is also discussed here.

English Abstract↗
PubMed2000

An epidemiological and ecological study of human alveolar echinococcosis transmission in south Gansu, China.

Human alveolar echinococcosis (AE) is usually a rare, highly pathogenic zoonotic disease, transmitted across the northern hemisphere between fox and rodent hosts. In China the first cases were described in 1965; however very few epidemiological studies have been undertaken since. Following identification in 1991 of a serious focus of human AE in south Gansu province, detailed village-based community and ecological studies were carried out between 1994 and 1997. Hepatic ultrasound mass screening with serological testing (five tests) identified 84/2482 new AE cases (3%). An overall prevalence of 4.1% (135/3331) was recorded for the area when previous cases were also included. Based on a seropositive result only, without an ultrasound scan indication, no additional AE cases were identified. Of the evolutive AE cases, 96% were seropositive in at least one test, while up 15-20% of individuals who exhibited hepatic calcified lesions and 12-15% exhibiting hepatic nodular lesions were seropositive for specific Em2 or Em18 antibodies. Village (n=31) human AE prevalence rates varied from 0 to 15.8%. Questionnaire analysis indicated that total number of dogs owned over a period was a risk factor (P<0.006), but not a history of red fox hunting (P>0.6). Rodent ecology studies revealed an association between density indices of voles (Microtus limnophilus) and village AE prevalence rates, on the one hand, and village landscape characterised by a ratio of scrub/grassland to total area above 50% (P<0.005). Long-term transmission of Echinococcus multilocularis and risk of zoonotic infection of south Gansu farmers may be related ultimately to a process of deforestation driven by agriculture. This in turn probably results in creation of optimal peri-domestic habitats for rodents that serve as intermediate host species (such as M. limnophilus) and subsequent development of a peri-domestic cycle involving dogs.

Adult↗
PubMed2000

Crystal structure of human ornithine transcarbamylase complexed with carbamoyl phosphate and L-norvaline at 1.9 A resolution.

The crystal structure of human ornithine transcarbamylase (OTCase) complexed with carbamoyl phosphate (CP) and L-norvaline (NOR) has been determined to 1.9-A resolution. There are significant differences in the interactions of CP with the protein, compared with the interactions of the CP moiety of the bisubstrate analogue N-(phosphonoacetyl)-L-ornithine (PALO). The carbonyl plane of CP rotates about 60 degrees compared with the equivalent plane in PALO complexed with OTCase. This positions the side chain of NOR optimally to interact with the carbonyl carbon of CP. The mixed-anhydride oxygen of CP, which is analogous to the methylene group in PALO, interacts with the guanidinium group of Arg-92; the primary carbamoyl nitrogen interacts with the main-chain carbonyl oxygens of Cys-303 and Leu-304, the side chain carbonyl oxygen of Gln-171, and the side chain of Arg-330. The residues that interact with NOR are similar to the residues that interact with the ornithine (ORN) moiety of PALO. The side chain of NOR is well defined and close to the side chain of Cys-303 with the side chains of Leu-163, Leu-200, Met-268, and Pro-305 forming a hydrophobic wall. C-delta of NOR is close to the carbonyl oxygen of Leu-304 (3.56 A), S-gamma atom of Cys-303 (4.19 A), and carbonyl carbon of CP (3.28 A). Even though the N-epsilon atom of ornithine is absent in this structure, the side chain of NOR is positioned to enable the N-epsilon of ornithine to donate a hydrogen to the S-gamma atom of Cys-303 along the reaction pathway. Binding of CP and NOR promotes domain closure to the same degree as PALO, and the active site structure of CP-NOR-enzyme complex is similar to that of the PALO-enzyme complex. The structures of the active sites in the complexes of aspartate transcarbamylase (ATCase) with various substrates or inhibitors are similar to this OTCase structure, consistent with their common evolutionary origin.

Aspartate Carbamoyltransferase↗
PubMed2000

In vitro bioactive behavior of hydroxylapatite-coated porous Al(2)O(3).

To produce bioactive materials for bone substitutes, two major deposition methods, suspension method and thermal deposition method, were employed to develop bioactive, mechanically strong, and porous ceramics. Hydroxylapatite (HA) has been uniformly coated onto inner pore surfaces of reticulated alumina substrates. It has been found that the in vitro bioactivity of HA coatings was affected by both structural crystallinity and specific surface area. Well-crystallized HA heat-treated at high temperatures has resulted in reduced bioactivity. The bio-reaction rate was found to increase with the surface area of HA. We have found that the stability of the well-crystallized HA is associated with the high driving force required for the formation of hydroxy-carbonate apatite (HCA) phase.

Aluminum Oxide↗
PubMed2000

Cryoatomic force microscopy of filamentous actin.

Cryoatomic force microscopy (cryo-AFM) was used to image phalloidin-stabilized actin filaments adsorbed to mica. The single filaments are clearly shown to be right-handed helical structures with a periodicity of approximately 38 nm. Even at a moderate concentration ( approximately 10 microg/ml), narrow, branched rafts of actin filaments and larger aggregates have been observed. The resolution achieved is sufficient to resolve actin monomers within the filaments. A closer examination of the images shows that the branched rafts are composed of up to three individual filaments with a highly regular lateral registration with a fixed axial shift of approximately 13 nm. The implications of these higher-order structures are discussed in terms of x-ray fiber diffraction and rheology of actin gels. The cryo-AFM images also indicate that the recently proposed model of left-handed F-actin is likely to be an artifact of preparation and/or low-resolution AFM imaging.

Actin Cytoskeleton↗
PubMed2000

Role of frizzled 7 in the regulation of convergent extension movements during gastrulation in Xenopus laevis.

Wnt signalling plays a crucial role in the control of morphogenetic movements. We describe the expression and functional analyses of frizzled 7 (Xfz7) during gastrulation in Xenopus. Low levels of Xfz7 transcripts are expressed maternally during cleavage stages; its zygotic expression strongly increases at the beginning of gastrulation and is predominantly localized to the presumptive neuroectoderm and deep cells of the involuting mesoderm. Overexpression of Xfz7 in the dorsal equatorial region affects the movements of convergent extension and delays mesodermal involution. It alters the correct localization, but not the expression, of mesodermal and neural markers. These effects can be rescued by extra-Xfz7, which is a secreted form of the receptor that also weakly inhibits convergent extension when overexpressed. This suggests that the wild-type and truncated receptors have opposing effects when coexpressed and that overexpression of Xfz7 causes an increased signalling activity. Consistent with this, Xfz7 biochemically and functionally interacts with Xwnt11. In addition, Dishevelled, but not (&bgr;)-catenin, synergizes with Xfz7 to affect convergent extension. Furthermore, overexpression of Xfz7 and Xwnt11 also affects convergent extension in activin-treated animal caps, and this can be efficiently reversed by coexpression of Cdc42(T17N), a dominant negative mutant of the small GTPase Cdc42 known as a key regulator of actin cytoskeleton. Conversely, Cdc42(G12V), a constitutively active mutant, rescues the effects of extra-Xfz7 on convergent extension in a dose-dependent manner. That both gain-of-function and loss-of-function of both frizzled and dishevelled produce the same phenotype has been well described in Drosophila tissue polarity. Therefore, our results suggest an endogenous role of Xfz7 in the regulation of convergent extension during gastrulation.

Adaptor Proteins, Signal Transducing↗
PubMed2000

[Effects of Ca2+, ABA and H3PO4 on relaxing stress of Na2CO3 and NaCl].

Two groups of Aneurolepidium chinense seedlings were stressed by 300 mmol.L-1 NaCl and 100 mmol.L-1 Na2CO3, respectively and the effect of ABA, Ca2+ and H3PO4 on relaxing their stress was studied. The results show that external Ca2+, ABA and H3PO4 could obviously mitigat the inhibitory effect of NaCl and NaCO3 on seedling growth. In the treatment of Na2CO3, praying it on leaves had a better effect than root-irrigating, while in the treatment of NaCl, there was no significant difference. The effect of Ca(NO3)2 was much better than that of CaCl2, and of mingling CaCl2 and ABA had a much better effect than CaCl2 or ABA alone.

Abscisic Acid↗
PubMed2000

Clinicopathologic analysis of angiomyofibroblastoma of the female genital tract.

OBJECTIVE: To study the clinicopathologic features and immunoprofile of angiomyofibroblastoma (AMF) with emphasis on differential diagnosis. METHODS: Seven vulvar, two vaginal and one perineal angiomyofibroblastomas were evaluated by light microscopy and immunohistochemistry. The immunohistochemical studies were performed on paraffin-embedded sections using the standard ABC method with a panel of antibodies. RESULTS: Angiomyofibroblastoma predominantly occurred in middle-aged women in the genital region, especially in the superficial area of the vulva. Clinically, most of the tumors presented as slowly growing painless masses and were often diagnosed as Bartholin's gland cysts. Histologically, the tumors were all well-circumscribed and characterized by alternating hypocellular and hypercellular areas with abundant thin-walled blood vessels. The tumor cells were bland and spindle-shaped or epithelioid and tended to concentrate around the vessels or cluster in small nests. Immunohistochemically, the tumor cells expressed vimentin and estrogen receptor protein in all 10 cases and desmin in 9 cases. Three cases showed weak or focal immunoreactivity to alpha-smooth muscle actin and muscle specific actin. All ten patients were treated by local excision. Follow-up showed a benign course with no signs of recurrence. CONCLUSIONS: Angiomyofibroblastoma is a distinctive neoplasm that has a propensity to occur in the female genital tract. Recognition of this entity is important to avoid misdiagnosis with other vulvar angiomyxoid neoplasms.

Adult↗
PubMed2000

[Clinical effect of Xiongshao capsule on preventing restenosis post-PTCA or/and stenting].

OBJECTIVE: To evaluate the effect of Xiongshao capsule (XSC) in preventing clinical and angiographic restenosis after coronary angioplasty or/and stenting. METHODS: Sixty-five coronary heart disease (CHD) patients with successful angioplasty or and stenting were randomly divided into the control group (37 cases, routine treatment) and the XSC group (28 cases, routine treatment plus XSC). The recurrent of angina, changing of blood stasis syndrome score (BSSS) and coronary angiography within 6 months after coronary angioplasty or/and stenting were observed. RESULTS: Recurrent angina occurred in 6 out of 28 patients in the XSC group, which was much better than that in the control group, 18 out of 37 patients (P < 0.05). Follow-up angiography was performed in 26 including 10 patients in the XSC group (restenosis was observed in 4 cases), and 16 cases in the control group (restenosis in 13 cases), there was significant difference between the XSC group and the control group (P < 0.05). For BSSS at follow-up, XSC group was much lower than that of the control group (P < 0.01). Logistic regress analysis showed the combination with XSC and the base-line BSSS were important affecting factors on the occurrence of restenosis (P < 0.05). The odds ratio of the occurrence of angiographic restenosis (BSSS > 25 to BSSS < or = 25) was 6.5. CONCLUSIONS: XSC could markedly reduce the occurrence of restenosis, recurrence of angina and improve the condition of blood stasis after coronary angioplasty or/and stenting. The severity of blood stasis syndrome was an important affecting factor on the occurrence of restenosis. BSSS > 25 can be served as one of the predicting factors of the occurrence of restenosis after coronary angioplasty or/and stenting.

Adult↗
PubMed2000

[Association of HLA-DRB1 allele and the susceptibility to alveolar echinococcosis in the west of China].

OBJECTIVE: To investigat the association of HLA-DRB1 alleles and the susceptibility to alveolar echinococcosis (AE). METHODS: Thirty-five patients with AE in the high prevalence areas in the west of China were investigated for HLA-DRB1 gene by PCR/SSP technique. The results were compared with 104 normal healthy peoples. RESULTS: Frequency of HLA-DRB1 * 040x was 26% in patient group, which was significantly higher than in control group (9.62%), with a relative risk (RR) of 4.45 (chi(2) = 13.67, P < 0.01), and with an etiological fraction of 0.20. Frequency of HLA-DRB1 * 0701 allele was decreased in patient group (patient 2.86%, control 13.94%; chi(2) = 6.67, P < 0.05), with preventable fraction of 0.30. While the frequencies of other DRB1 alleles were not significantly different. CONCLUSION: Susceptibility to AE is strongly associated with the HLA-DRB1 * 040x allele. The high prevalence of human AE in this region was associated with genetic factor. HLA-DRB1 * 0701 geners resistant to Echinococcus multilocularis metacestode infection.

Adolescent↗
PubMed2000

[Measurement of T and DHT contents in normal and diseased human prostate tissues].

OBJECTIVE: To measure T and DHT contents in normal and diseased human prostate tissues. METHODS: Serum and prostatic T and DHT levels were measured in patients with normal, benign prostatic hyperplasia and prostate cancer. RESULTS: A decline was observed in serum T level, but no change in DHT concentration with aging. There were no significant differences in both blood T and DHT levels between the patients with BPH or PCA and normal controls. Serum T level remained constant. There were excessive accumulation of DHT in BPH, and cancerous prostate tissues were responsible for the pathogenesis of BPH and PCA. Finasteride treatment did not produce a reduction in prostatic DHT content. CONCLUSION: More than one form of 5a-reductases is responsible for the high level of DHT in the gland.

Adult↗
PubMed2000

[A diagnostic analysis of imaging in ocular cysticercosis].

OBJECTIVE: To discuss B-ultrasonography, CT and MRI appearances and image diagnostic value for ocular cysticercosis. METHOD: In the 29 cases with ocular cysticercosis, 21 cases were examined by B-ultrasonography, 19 cases by X-ray computed tomography (CT) and 6 cases by magnetic resonance imaging (MRI). RESULTS: At the living stage of the cysticercus, B-ultrasound might detect parasitic cyst and its movement in the eyeball and orbit, extraocular muscle irregular hyperplasia; CT might detect parasitic cyst in the orbit and the pathologic extraocular muscle; MRI might detect the parasitic cyst in the eyeball and the orbit and the pathologic extraocular muscle. At the non-living stage of the cysticercus, B-ultrasonography and CT might discover calcification focus in the eyeball and extraocular muscle. CONCLUSION: Image appearances of ocular cysticercosis depend on the parasitic site and living status of cysticercus in the eye region. For diagnosis, B-ultrasonography may first be selected, MRI secondly selected for living stage and CT secondly selected for non-living stage of the ocular cysticercosis.

Adolescent↗