Biomedical subjects

X Yang

Publications and source records attributed to X Yang.

At least 433 records · Page 24Linked to original sources

PubMed2000

[IL-4 gene transfer induces the differentiation of cells and inhibits the activity of telomerase in hepatoblastoma cells].

OBJECTIVE: To investigate the effects of human interleukin-4(hIL-4) gene transfer on the differentiation and the activities of telomerase in hepatoblastoma cells. METHODS: Retroviral vector (PL-IL-4-SN) was employed to introduce hIL-4 gene into human hepatoblastoma cell line(Hep G2)cells. Trypan blue and Wright's stain, radioimmunoassay, in situ hybridization, flow cytometry, PCR-ELISA were used to determine the change in morphology and cell cycle, the expression of proto-oncogenes, the synthesis of AFP and the activities of telomerase in IL-4 gene transferred tumor cells. RESULTS: The shape of the hepatoblastoma cells tended to become relatively mature; the growth of the cells was significantly suppressed(P<0.05); the synthesis of AFP was reduced from 15.36+/-0. 67 ng x10(6) cells(-1); x24h(-1); to 3.26 +/- 1.43ng x10(6) cells(-1); x 24h(-1); the proliferation of the cells was significantly suppressed(P<0.05); the cell cycle was arrested at G(0)/ G(1) stage; the expression of c-fos, c-jun, c-myc and the activities of telomerase were remarkably decreased in IL-4 gene-modified Hep G2 cells. CONCLUSION: hIL-4 gene transfer could induce the differentiation of heptoblastoma cells and down-regulate the activity of tolemarase in Hep G2 cells.

Cell Differentiation↗

PubMed2000

Late-onset holocarboxylase synthetase deficiency with homologous R508W mutation.

Holocarboxylase synthetase (HCS) is responsible for the biotinylation of pyruvate carboxylase, propionyl coenzyme A (CoA) carboxylase, beta-methylcrotonoyl CoA carboxylase, and acetyl CoA carboxylase. We report on a patient with HCS deficiency resulting in a rare metabolic disease. The patient, a 2-year-old boy, presented with vomiting, consciousness disturbance, and dyspnea. Laboratory examinations showed hyperglycemia, hyperammonemia, lactic acidosis, and excretion of large amounts of beta-hydroxyisovalerate and beta-methylcrotonylglycine in the urine. After 10 days of treatment with biotin 5 mg.kg-1.day-1, the abnormal organic acids in his urine had almost completely disappeared. There were no subsequent attacks, and his growth and development remained normal during 1 year of follow-up. Nucleotide sequence analysis of the HCS cDNA of the patient revealed a homozygous 1809C-->T (R508W) mutation. The R508W mutation is found worldwide, and might be associated with higher residual HCS activity than other mutations. Late-onset HCS deficiency cannot be differentiated clinically from biotinidase deficiency. Prompt and correct diagnosis is important for these biotin-responsive disorders.

Carbon-Nitrogen Ligases↗

PubMed2000

Ethanol modulation of gamma-aminobutyric acid (GABA)-mediated inhibition of cerebellar Purkinje neurons: relationship to GABAb receptor input.

BACKGROUND: Electrophysiological recording reveals that only a portion of cerebellar Purkinje neurons are sensitive to ethanol enhancement of gamma-aminobutyric acid (GABA) responses. Although activation of beta-adrenergic receptors permits ethanol enhancement of GABA function from some cerebellar Purkinje neurons, other neurons remain insensitive to ethanol. These findings are consistent with the finding that other external neural inputs are required to allow ethanol enhancement of GABA responses from Purkinje neurons. Because of a high expression of GABA(B) receptors on Purkinje cells, we tested whether activation of GABA(B) receptors might modulate the action of ethanol on GABA responsiveness. METHODS: Extracellular single-unit electrophysiological recording was used to investigate the effects of ethanol on responses to GABA and muscimol (a GABA(A) agonist) from cerebellar Purkinje neurons. Drugs tested were baclophen (a GABA(B) agonist) and CGP35348 (a GABA(B) antagonist). RESULTS: Ethanol did not enhance responses to GABA and muscimol from all Purkinje neurons. Systemic administration of the GABA(B) agonist, baclophen (3 mg/kg intravenously), permitted ethanol to enhance GABA inhibition from approximately 75% of cerebellar Purkinje neurons not initially enhanced by ethanol. Local iontophoretic application of baclophen to Purkinje neurons also allowed ethanol to enhance GABA and muscimol responsiveness from a portion of neurons in which ethanol initially did not affect their actions. An inhibitory action of ethanol on responses to GABA and muscimol, which was also influenced by baclophen, was observed from some Purkinje neurons. From Purkinje neurons initially sensitive to ethanol enhancement of GABA and muscimol function, administration of CGP35348, a GABA(B) antagonist, diminished the effect of ethanol on the responsiveness of these agonists from the majority (9/15) of neurons. CONCLUSIONS: The present findings demonstrated that baclophen allows ethanol enhancement of GABA and muscimol responsiveness from some, but not all, cerebellar Purkinje neurons initially not sensitive to ethanol. Likewise, a GABA(B) antagonist can diminish ethanol enhancement of GABA and muscimol responses from some ethanol-sensitive neurons. Thus, these results emphasize that GABA(B) receptors on a portion of Purkinje neurons act as an auxiliary neural input that allows ethanol enhancement of GABA responses. Consequently, receptor structure alone does not account for the action of ethanol on GABA(A) receptor function on this cell type.

Animals↗

PubMed2000

Immunohistochemical analyses of focal adhesion kinase expression in benign and malignant human breast and colon tissues: correlation with preinvasive and invasive phenotypes.

The focal adhesion kinase (FAK) is a protein tyrosine kinase linked to signaling events between cells and the extracellular matrix. Studies at the Western blot level have demonstrated up-regulation of FAK expression in invasive breast and colon cancers. To assess p125FAK expression at the cellular level, we developed monoclonal antibodies that specifically detected FAK in formalin-fixed, paraffin-embedded tissue sections and analyzed the levels of FAK expression in human breast and colon tissues. Monoclonal antibody 4.47 demonstrated FAK-specific focal adhesion staining by immunofluorescence assays on BT-474 breast cancer cells and detected a Mr 125,000 protein by both Western blotting and immunoprecipitation analyses. Using immunohistochemical techniques, the expression of p125FAK was analyzed in 36 normal and 43 preinvasive or invasive human breast and colon tissues from individual patients. FAK was weakly expressed in most benign breast epithelium but was up-regulated at moderate or strong levels in 14 of 18 invasive breast carcinomas. In seven samples of ductal carcinoma-in situ, FAK was overexpressed. Borderline-to-weak expression of FAK was detected in the normal colonic epithelium. In the invasive colon cancers, FAK was overexpressed at moderate or strong levels in 13 of 15 tumors. Furthermore, FAK expression was up-regulated in areas of dysplastic, premalignant colon epithelium. These results provide the first evidence at the cellular level that FAK expression is variably overexpressed in breast and colon cancer and suggest that up-regulation occurs at an early stage of tumorigenesis.

Animals↗

PubMed2000

[3-D direct matching interpolation for rotary scanning echo-cardial images].

In the present paper, a method of three dimension direct matching interpolation for a series of 2-D echo-cardial images with intersecting each other and arranging at an angle in space has been developed. It is different from the conventional interpolation. During the interpolation, sectional images are acquired and the 3-D spatial position of "empty voxel" in sectional images is located; secondly, the cubic volume is constructed, and the motion orbit of images between two windows where the nearest original image intersects to the volume is found up, passing through the "empty voxel"; In the end, based on the matching pixels, the "empty voxel" is interpolated. This method simplifies the two interopolating procedures of the conventional methods into one procedure, and overcomes the shortcoming of the overlap of image data. Experiments show that the accuracy and reasonability of interpolation can be improved by the proposed method.

Echocardiography↗

PubMed2000

[Remodeling and biomechanical properties of thoracic aorta in spontaneously hypertensive rats].

Morphometry and microstructure of thoracic aorta of spontaneously hypertensive rats (SHR) at different periods before and after hypertension were studied quantitatively by histological method and computer image analysis. We also observed the changes of opening angle in the zero-stress state and the relationship between pressure and diameter in SHR during established hypertension. The results showed that with blood pressure chronically increasing, there was a significant increase in morphometric parameters and microstructure parameters of the thoracic aorta in SHR. The zero-stress state of opening angle in SHR during established hypertension increased significantly. These reults suggest that aortic structural remodeling in hypertension such as thickness of vascular wall and disproportional increase of collagen may lead to decrease in distensibility of the aorta in SHR. The structural remodeling and changes of mechanical properties in aorta may contribute to the important pathophysiology of hypertension-induced complications.

Animals↗

PubMed2000

Ethanol uses cAMP-independent signal transduction mechanisms to activate proenkephalin promoter activity in rat C6 glioma cells.

BACKGROUND: Previous in vivo studies show that acute ethanol exposure sequentially increases protein kinase A (PKA) activity, the phosphorylation of the adenosine 3':5'-cyclic monophosphate (cAMP)-dependent transcription factor, CREB, and finally proenkephalin gene expression. The present study was conducted to determine if ethanol could activate directly the adenylyl cyclase pathway and thus enhance proenkephalin promoter activity. METHODS: Cultured rat C6 glioma cells stably transfected with a segment of the five prime flanking region of rat proenkephalin promoter (nucleotide -2700+/-53) ligated to the chloramphenicol acetyltransferase (CAT) reporter gene were employed to study the effects of ethanol on proenkephalin promoter activity. This region of proenkephalin promoter contains two cAMP response elements (CRE-1 and CRE-2) and one AP2 site located in the region upstream of the TATA box. Cultures were exposed to ethanol, isoproterenol, and phorbol-12, myristate 13-acetate (PMA) alone and in combination, in the presence and absence of PKA and protein kinase C (PKC) inhibitors. RESULTS: Ethanol and isoproterenol increased proenkephalin promoter activity in a dose-dependent manner. Ethanol had an additive effect on maximal isoproterenol-stimulated proenkephalin promoter activity, which suggested that ethanol used a cAMP-independent signal transduction pathway to increase proenkephalin promoter activation. In contrast with isoproterenol, ethanol exposure did not increase cAMP accumulation, PKA activity, or the phosphorylated form of CREB. However, ethanol exposure modestly increased PKC activity. The PKA-specific inhibitor, Rp-cAMP, dampened isoproterenol-induced activation of CAT activity but did not alter ethanol's ability to increase CAT activity. However, the PKC inhibitors, chelerthyrine and G07874, abrogated ethanol's effect of CAT activity but did not alter isoproterenol's effects. CONCLUSIONS: Ethanol enhanced proenkephalin promoter activity and potentiated isoproterenol-stimulated promoter activity through a cAMP-independent pathway.

Adrenergic beta-Agonists↗

PubMed2000

Chlamydia trachomatis mouse pneumonitis lung infection in IL-18 and IL-12 knockout mice: IL-12 is dominant over IL-18 for protective immunity.

BACKGROUND: Interferon (IFN)-gamma is a key to protective immunity against a variety of intracellular bacterial infections, including Chlamydia trachomatis. Interleukin (IL)-18, a recently identified Th1 cytokine, together with IL-12 is a strong stimulator for IFN-gamma production. We investigated the relative roles of IL-18 and IL- 12 in protective immunity to C. trachomatis mouse pneumonitis (MoPn) infection using gene knockout (KO) and wild-type (WT) mice. MATERIALS AND METHODS: Mice were intranasally infected with C. trachomatis MoPn and protective immunity was assessed among groups of mice by daily body weight changes, lung growth of MoPn, and histopathological appearances at day 10 postinfection. The corresponding immune responses for each group of mice at the same postinfection time point were evaluated by measuring antigen-specific antibody isotype responses and cytokine profiles. RESULTS: Our results showed that IL-18 deficiency had little or no influence on clearance of MoPn from the lung, although KO mice exhibited slightly more severe inflammatory reactions in lung tissues, as well as reduced systemic and local IFN-gamma production, compared with WT mice. Results with IL-18 KO mice were in sharp contrast to those observed with IL-12 KO mice that showed substantially reduced clearance of MoPn from the lungs, substantial reductions of antigen-specific systemic and lung IFN-gamma production, decreased ratio of MoPn-specific immunoglobulin G (IgG)2a/IgG1, and severe pathological changes in the lung with extensive polymorphonuclear, instead of mononuclear, cell infiltration. Exogenous IL-12 or IL-18 was able to increase IFN-gamma production in IL-18 KO mice; whereas, only exogenous IL-12, but not IL-18, enhanced IFN-gamma production in IL-12 KO mice. Caspase-1 is the key protease for activation of IL-18 precursor into the bioactive form, and caspase-1 KO mice also displayed similar bacterial clearance and body weight loss to that in WT mice at early stages of MoPn infection. This further confirmed that IL-18 was not essential for host defense against chlamydia infection. CONCLUSIONS: These results suggest that IL-12, rather than IL-18, plays the dominant role in the development of protective immunity against chlamydia lung infection, although both cytokines are involved in the in vivo regulation of IFN-gamma production.

Animals↗

PubMed2000

KAI1 protein is down-regulated during the progression of human breast cancer.

The KAI1 gene was identified as a metastasis suppressor gene for human prostate cancer. Recently, we showed that KAI1 mRNA levels were higher in an immortal, normal-like breast epithelial cell line and nonmetastatic breast cancer cell lines but lower substantially in highly metastatic breast cancer cell lines. In this study, we examined KAI1 protein expression in breast cancer cell lines by Western blot and immunohistochemical study. KAI1 protein levels paralleled KAI1 mRNA levels and were inversely correlated with the metastatic potential of breast cancer cells. Furthermore, we examined KAI1 protein expression immunohistochemically in specimens from 81 patients with breast cancer and then correlated the findings with the clinical and histopathological parameters of the patients. High levels of KAI1 protein expression were found in normal breast tissues and noninvasive breast cancer (ductal carcinoma in situ). In contrast, KAI1 expression was reduced in most of the infiltrating breast tumors. We found that, in general, more malignant tumors demonstrated significantly lower KAI1 expression (P = 0.004). Additionally, among 29 specimens demonstrating multiple stages of malignancy within a single specimen, 23 demonstrated significant differences in KAI1 expression between benign breast tissue, ductal carcinoma in situ, and invasive carcinoma. The higher the incidence for malignancy within a given specimen, the lower the KAI1 expression (P < 0.001). These data suggest that in advanced breast cancer, KAI1 expression is down-regulated. Therefore, KAI1 may be a potentially useful indicator of human breast cancer progression.

Antigens, CD↗

PubMed2000

Expression of protein mediators of type I interferon signaling in human squamous cell carcinoma of the skin.

IFN-based therapy has been shown to be active in the treatment of squamous cell carcinoma (SCC) of the skin and has promise for chemoprevention and treatment of several other cancers. In an effort to better understand the molecular mechanism of this activity, we have determined the expression pattern of several of the protein mediators of type I IFN signaling by immunohistochemistry in cutaneous SCC, SCC metastases, and adjacent nonmalignant epithelium from patient biopsies. All of the proteins, signal transducer and activator of transcription (STAT) 1alpha/beta, STAT2, p48, STAT3a, and STAT3beta, are expressed at varying levels in the adjacent epidermis, as well as in other epidermal and dermal cell types. For the majority of samples tested, the expression of one or more of these proteins was reduced in SCC primary tumors compared with the adjacent nonmalignant epithelial cells, as determined by manual scoring. Quantitative densitometry of several samples revealed differences that are statistically significant. Our study provides the first direct evidence for the expression of the IFN-stimulated gene factor 3 (STAT1alpha/beta, STAT2, and p48) and STAT3alpha and STAT3beta mediators of IFN-alpha/beta signaling in human skin and skin-derived SCCs. These data have led to the hypothesis that the loss of IFN sensitivity may contribute to the development and progression of skin SCC.

Biomarkers, Tumor↗

PubMed2000

CD40 ligand expression on macrophages during peritonitis in continuous ambulatory peritoneal dialysis patients.

CD40-CD40 ligand (CD40L) interaction plays an important role in macrophage/monocyte-mediated inflammatory processes by up-regulating cytokine production by macrophages/monocytes and by preventing macrophage apoptosis at the inflammation sites. The present study investigated the possible regulation of CD40L expression in peritonitis during continuous ambulatory peritoneal dialysis (CAPD). We used fluorescence-activated cell sorter (FACS) analysis to detect CD40L expression on macrophages obtained from peritoneal dialysate. Our results showed that CD40L expression on macrophages was significantly increased in a peritonitis group (4.62 +/- 6.54) as compared to a control group (0.76 +/- 0.30, p < 0.01). The CD40L-positive cells were also significantly increased during peritonitis (97.86% +/- 1.67% in the peritonitis group as compared to 73.10% +/- 26.94% in the control group, p < 0.05). After successful treatment, the expression of CD40L was significantly reduced (3.66 +/- 1.12 vs 1.05 +/- 0.02, p < 0.05). We conclude that functionally expressed CD40L on macrophages may take part in acute inflammatory response during peritonitis in CAPD and may play an important role in the local defense against infection in the peritoneal cavity.

Acute Disease↗

PubMed2000

[The adsorption on attapulgite and cross-linked agar beads entrapped attapulgite(CAA)].

The adsorption of four drugs with certain toxicity, i.e. chlorpromazine, quinidine, diazepam and phenobarbital on attapulgite and Cross-linked Agar Beads Entrapped Attapulgite(CAA) was determined in this study. The results revealed that attapulgite possessed high adsorption for the cation drugs(chlorpromazine and quinidine), moderate adsorption for diazepam, and slight adsorption for phenobabital. The adsorption in attapulgite was quite quick and came to equilibrium in about 30 min. No significant difference(P > 0.05) of adsorption on attapulgite was observed at 30 min and 60 min. The adsorbent selectivity on CAA was the same as that on attapulgite. The speed of the adsorption was slower on CAA than on attapulgite, but the quantity adsorpted on CAA and that on attapulgite had no marked difference(P > 0.05) after 60 min. CAA preserved the adsorption property of attapulgite fundamentally. CAA overcame the dispersibility of attapulgite distinctly and showed good hemocompatibility and a fair blood flow rate in hemoperfusion. It may play an important role in the separation of blood components and in hemopurification.

Adsorption↗

PubMed2000

[Research on the relationship between expression of VEGF and high altitude pulmonary edema].

OBJECTIVE: To investigate the relationship between the expression of VEGF and the incidence of high altitude pulmonary edema (HAPE) and the mechanism of high altitude acclimatization-adaptation. METHODS: Pulmonary artery endothelial cells (PAEC) of rat were cultured. The expression of VEGF in PAEC was detected using RT-PCR and ELISA. Rats were divided randomly into five groups by weight: control, acute hypoxia (exposed to a simulated 8,000 m altitude for 4 hours), and three intermittent hypoxia groups (exposed to a simulated 3,000 m or 5,000 m altitude for 2 weeks, 4 hours a day, then to a simulated 8,000 m altitude for 4 hours). VEGF in the lung was detected using immunohis to chemistry and slot hybridization, and the changes of pathology in the lung were observed. VEGF in the blood plasma of rats, in men who immigrated to high altitude at different times, and in those who suffered from high altitude pulmonary edema were measured using ELISA. RESULTS: The expression of VEGF in PAEC was increased under hypoxia condition (1% O2) (P < 0.01). In the blood plasma and lung of rats during hypoxia, levels of VEGF and VEGF mRNA were higher than that in the control group. VEGF in acute hypoxia group was increased significantly compared with that in the intermittent hypoxia groups. Leakage of fluid in the lung of rats was observed in the acute hypoxia group. The longer the rats acclimatized, the lower the level of VEGF expressed, and the less the fluid leaked in the lung. The same tendency could be seen in humans. The level of VEGF in patients with high altitude pulmonary edema pre-therapy was higher than that measured post-therapy. CONCLUSIONS: Hypoxia could stimulate the expression of VEGF, and the upregulated expression of VEGF is one of the most important factors of incidence of high altitude pulmonary edema.

Altitude Sickness↗

PubMed2000

[Clinical study of four cases with malignant gestation trophoblastic tumor after mifepristone abortion].

OBJECTIVE: To describe the clinical characteristics of malignant gestational trophoblastic tumor after medical abortion used by mifepristone combined with misoprostol and its diagnosis and differential diagnosis from incomplete abortion. METHODS: Four cases with malignant gestational trophoblast tumor after medical abortion were presented focusing on the clinical manifestation and the methods of diagnosis and differential diagnosis. RESULTS: Irregular vaginal bleeding and abnormal high level of beta-human chorionic gonadotropin (hCG) in plasma were the common manifestation of the gestational trophoblast tumour and incomplete abortion after medical abortion. However, beta-hCG of the former after curettage was still higher by dynamic monitoring. Malignant gestational trophoblast tumor showed rich blood flow signal and low blood flow resistance index (RI, RI < 0.5) in uterus in color doppler echography, digital subtraction angiography (DSA) with abnormal enlargement of the arteria of uterine, arteriovenous fistula beside the uterine were the main characteristics of malignant gestational trophoblast tumour. CONCLUSIONS: Pay attention to the early stage malignant gestational trophoblast tumour among patients with abnormal vaginal bleeding after medical abortion. beta-hCG and DSA were the most effective methods to diagnose and differentially diagnose choriocarcinoma from the incomplete abortion among the patients with abnormal vaginal bleeding after medical abortion.

Abortifacient Agents, Steroidal↗

PubMed2000

[Application of Conners Rating Scales in the study of lead exposure and behavioral effects in children].

OBJECTIVE: To seek specific indices reflecting individual level of long-term exposure to lead and its behavioral effects. METHODS: Ninety-eight children of grades one to four in primary schools in the areas polluted by lead were chosen as exposed group and 100 children from areas without lead pollution as control group. Levels of blood lead, hair lead and blood zinc protoporphyrin (ZPP) in both groups were determined to evaluate their exposure to lead. Their urinary homovanillic acid (HVA) and vanillylmandelic acid (VMA) were determined by a method combined high-performance liquid chromatography (HPLC) with electric chemistry (EC) technique. Behavioral effects in children exposed to lead were assessed by Conners' Rating Scales for Teachers and Parents. RESULTS: Levels of blood lead, hair lead and blood ZPP in the exposed group increased to 2.39-2.42 mumol/L, 81.81-83.77 mumol/kg and 0.55-0.65 mumol/L in average, respectively, and levels of HVA and VMA decreased to 0.53 mmol/mol creatinine and 0.68 mmol/mol creatinine in average, respectively, both with a very significant difference as compared with those in the control group. There were significant differences in the scores of behavioral factors between the two groups. Factors I, IV and VI in Conners' Parents' Rating Scales correlated positively with levels of hair lead, while factors I, II, IV and VI correlated positively with blood ZPP levels in girls. CONCLUSION: Conners' Rating Scales for Teachers and Parents can be used to assess their behavioral effects in children, and levels of hair lead and blood lead can be used as good markers to reflect level of exposure to lead in children.

Attention Deficit Disorder with Hyperactivity↗

PubMed2000

[Side effects after treatment with a-interferon in children with chronic viral hepatitis].

OBJECTIVE: This paper aimed at a long-term observation on side effects of alpha- IFN treatment in children with chronic viral hepatitis. METHODS: A randomized trial of 261 alpha-IFN treated chronic hepatitis children (183 with hepatitis B, 78 with hepatitis C) in comparison with 114 adults was carried out to observe side effect of alpha-IFN treatment 5-6 years in average and 10 years the longest. Mean age of children was 8.7 years, with 203 males and 58 females. RESULTS: Early stage side effects were low to moderate fever and endemic influenza symptoms, which in children were more less than in adults (P < 0.001). Side effects did not relate to viral pathogeny (HB or HC) and pathological changes (< or = G2, > or = G3) in child patient. Slightly poor appetite, slight hair loss, rash and tinnitus would disappear gradually needed no treatment. Serum Bil, Bun, Cr, T3, T4 and TSH were normal in all patients. There was no long-term side effects. CONCLUSIONS: alpha-IFN treatment for viral hepatitis in children is safe.

Adult↗

PubMed2000

[Parasitic metamorphosis development of Lamprotula fibrosa].

The glochidia of Lamprotula fibrosa develop to maturity in the outer gill of female and are expelled to the outside in winter, and then, the mature glochidia are parasitized to the gill of fish host and start the parasitic metamorphosis development. The parasitic period lasts about 4 months. The inner and outer byssuses disappear after parasitizing for 3 days. The foots develop after 35 days. The intestine, adductor muscle, nephridium and gill anlage develop after 90 days. The shells become thick and protrusive. The glochidia become larvae with a size of 253.37 x 273.26 x 179.96 microns in the next spring, then leave the gill of fish host, and start their independent life.

Animals↗

PubMed2000

[Comparison analysis between potential and actual pattern of artificial oases in arid region].

Based on theoretical analysis and demonstration research, the conception of potential pattern in the agriculture landscape of artificial oases in Xinjiang arid region and its analysis unit were discussed. The potential landscape pattern was defined as the one composed by spatial units with basic characteristics and properties which had no change or less change with the time. In agriculture landscape, soil was found to be a relatively stable element, and hence, different soil classification unit could be used to analyze the potential landscape pattern. A case study was carried out to analyze the potential and actual pattern of the artificial cases in Shihezi reclamation area by using the indexes of diversity, evenness, aggregation, mean patch elongation, patch shape fragmentation and mean patch fractal dimension. The result showed that the landscape pattern changed orderly from the potential to actual pattern, and the potential pattern could be used as the absolute criterion for researches on pattern changes in agriculture landscape.

Agriculture↗