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PubMed2004

Hedgehog-interacting protein is highly expressed in endothelial cells but down-regulated during angiogenesis and in several human tumors.

BACKGROUND: The Hedgehog (Hh) signaling pathway regulates a variety of developmental processes, including vasculogenesis, and can also induce the expression of pro-angiogenic factors in fibroblasts postnatally. Misregulation of the Hh pathway has been implicated in a variety of different types of cancer, including pancreatic and small-cell lung cancer. Recently a putative antagonist of the pathway, Hedgehog-interacting protein (HIP), was identified as a Hh binding protein that is also a target of Hh signaling. We sought to clarify possible roles for HIP in angiogenesis and cancer. METHODS: Inhibition of Hh signaling by HIP was assayed by measuring the induction of Ptc-1 mRNA in TM3 cells treated with conditioned medium containing Sonic hedgehog (Shh). Angiogenesis was assayed in vitro by EC tube formation on Matrigel. Expression of HIP mRNA was assayed in cells and tissues by Q-RT-PCR and Western blot. HIP expression in human tumors or mouse xenograft tumors compared to normal tissues was assayed by Q-RT-PCR or hybridization of RNA probes to a cancer profiling array. RESULTS: We show that Hedgehog-interacting protein (HIP) is abundantly expressed in vascular endothelial cells (EC) but at low or undetectable levels in other cell types. Expression of HIP in mouse epithelial cells attenuated their response to Shh, demonstrating that HIP can antagonize Hh signaling when expressed in the responding cell, and supporting the hypothesis that HIP blocks Hh signaling in EC. HIP expression was significantly reduced in tissues undergoing angiogenesis, including PC3 human prostate cancer and A549 human lung cancer xenograft tumors, as well as in EC undergoing tube formation on Matrigel. HIP expression was also decreased in several human tumors of the liver, lung, stomach, colon and rectum when compared to the corresponding normal tissue. CONCLUSION: These results suggest that reduced expression of HIP, a naturally occurring Hh pathway antagonist, in tumor neo-vasculature may contribute to increased Hh signaling within the tumor and possibly promote angiogenesis.

Animals↗
PubMed2005

Structural organization and interactions of transmembrane domains in tetraspanin proteins.

BACKGROUND: Proteins of the tetraspanin family contain four transmembrane domains (TM1-4) linked by two extracellular loops and a short intracellular loop, and have short intracellular N- and C-termini. While structure and function analysis of the larger extracellular loop has been performed, the organization and role of transmembrane domains have not been systematically assessed. RESULTS: Among 28 human tetraspanin proteins, the TM1-3 sequences display a distinct heptad repeat motif (abcdefg)n. In TM1, position a is occupied by structurally conserved bulky residues and position d contains highly conserved Asn and Gly residues. In TM2, position a is occupied by conserved small residues (Gly/Ala/Thr), and position d has a conserved Gly and two bulky aliphatic residues. In TM3, three a positions of the heptad repeat are filled by two leucines and a glutamate/glutamine residue, and two d positions are occupied by either Phe/Tyr or Val/Ile/Leu residues. No heptad motif is apparent in TM4 sequences. Mutations of conserved glycines in human CD9 (Gly25 and Gly32 in TM1; Gly67 and Gly74 in TM2) caused aggregation of mutant proteins inside the cell. Modeling of the TM1-TM2 interface in CD9, using a novel algorithm, predicts tight packing of conserved bulky residues against conserved Gly residues along the two helices. The homodimeric interface of CD9 was mapped, by disulfide cross-linking of single-cysteine mutants, to the vicinity of residues Leu14 and Phe17 in TM1 (positions g and c) and Gly77, Gly80 and Ala81 in TM2 (positions d, g and a, respectively). Mutations of a and d residues in both TM1 and TM2 (Gly25, Gly32, Gly67 and Gly74), involved in intramolecular TM1-TM2 interaction, also strongly diminished intermolecular interaction, as assessed by cross-linking of Cys80. CONCLUSION: Our results suggest that tetraspanin intra- and intermolecular interactions are mediated by conserved residues in adjacent, but distinct regions of TM1 and TM2. A key structural element that defines TM1-TM2 interaction in tetraspanins is the specific packing of bulky residues against small residues.

Algorithms↗
PubMed2004

The ATP-binding cassette transporter 1 mediates lipid efflux from Sertoli cells and influences male fertility.

The liver X receptor/retinoid X receptor (LXR/RXR)-regulated gene ABCA1 effluxes cellular cholesterol and phospholipid to apolipoprotein A1 (apoA1), which is the rate-limiting step in high-density lipoprotein synthesis. The RXR pathway plays a critical role in testicular lipid trafficking, and RXRbeta-deficient male mice are sterile and accumulate lipids in Sertoli cells. Here, we demonstrate that ABCA1 mRNA and protein are abundant in Sertoli cells, whereas germ cells express little ABCA1. LXR/RXR agonists stimulate ABCA1 expression in cultured Sertoli MSC1 and Leydig TM3 cell lines. However, Sertoli TM4 cells lack ABCA1, and TM4 cells or primary Sertoli cells cultured from ABCA1(-/-) mice both fail to efflux cholesterol to apoA1. Expression of exogenous ABCA1 restores apoA1-dependent cholesterol efflux in Sertoli TM4 cells. In vivo, ABCA1-deficient mice exhibit lipid accumulation in Sertoli cells and depletion of normal lipid droplets from Leydig cells by 2 months of age. By 6 months of age, intratesticular testosterone levels and sperm counts are significantly reduced in ABCA1(-/-) mice compared with wild-type (WT) controls. Finally, a 21% decrease (P = 0.01) in fertility was observed between ABCA1(-/-) males compared with WT controls across their reproductive lifespans. These results show that ABCA1 plays an important role in lipid transport in Sertoli cells and influences male fertility.

ATP Binding Cassette Transporter 1↗
PubMed1990

1,25-Dihydroxyvitamin D3 antagonizes interferon-gamma-induced expression of class II major histocompatibility antigens on thyroid follicular and testicular Leydig cells.

Interferon-gamma (IFN gamma) induces production and expression of major histocompatibility complex class II molecules on both marrow-derived and nonbone marrow-derived cell types. 1,25-Dihydroxyvitamin D3 [1,25-(OH)2D3], a seco-steroid derived from vitamin D3, has previously been reported to enhance such expression alone or together with IFN gamma on a number of monocyte/macrophage tumorigenic lines. In contrast, the present studies have found that 1,25-(OH)2D3 inhibited the ability of IFN gamma to induce class II antigen expression on nontransformed rat thyroid follicular epithelial cells (FRTL-5) and mouse testicular Leydig cells (TM3). Although 1,25-(OH)2D3 inhibited the induction of both IA and IE class II locus products, IFN gamma augmentation of class I major histocompatibility complex antigens was not affected. 1,24-(OH)2D3 and 24,25-(OH)2D3 also inhibited class II induction by IFN gamma. Notably, the relative inhibitory ability of these compounds paralleled the strength of their binding affinities for the 1,25-(OH)2D3 receptor, indicating that this antagonistic effect probably requires receptor-ligand interaction. Other steroid hormones, such as hydrocortisone or testosterone, had no inhibitory effect on IFN gamma-induced class II expression on Leydig cells. Additionally, the failure of indomethacin to reverse the effect of 1,25-(OH)2D3 and the finding that exogenous prostaglandin E2 did not inhibit class II induction in these cells indicated that prostaglandins are probably not responsible for this anti-IFN gamma activity. In total, these results suggest that an endocrinological mediator is capable of inhibiting class II induction on resident endocrine tissue populations and, therefore, could help to diminish local CD4+ T-cell recognition of these cells.

24,25-Dihydroxyvitamin D 3↗
PubMed1996

Macrophage migration inhibitory factor production by Leydig cells: evidence for a role in the regulation of testicular function.

Macrophage migration inhibitory factor (MIF), described originally as a product of activated T lymphocytes, recently has been found to be released by monocytes/macrophages and the anterior pituitary gland. Immunohistochemical studies of the adult rat testis using an affinity-purified polyclonal antimurine MIF antibody demonstrated strong staining for MIF in Leydig cells and their putative precursors. Peritubular myoid cells and the seminiferous epithelium were negative for MIF staining; however, a weak reaction around the heads of elongated spermatids also was observed. The expression of MIF messenger RNA and protein in whole rat testis was demonstrated by Northern blot and Western blot analyses, respectively. Both MIF messenger RNA and protein immunoreactivity in Leydig cells was observed in testes obtained from long term hypophysectomized rats. Significant concentrations of intracellular MIF were detected in lysates of the TM3 Leydig cell line (7.23 +/- 2.6 pg/microgram protein), and testicular interstitial fluid contained 14.7 +/- 1.6 ng/ml MIF protein, as measured by MIF-specific enzyme-linked immunosorbent assay. To gain insight into the possible biological role of MIF in the testis, cultures of adult rat seminiferous tubules and purified Leydig cells were incubated together with recombinant murine MIF (rMIF). Neither rMIF (50 ng/ml) nor a neutralizing anti-MIF antiserum was found to affect basal or LH-stimulated Leydig cell steroidogenesis in vitro. However, a dose-dependent decrease in the secretion of inhibin by the seminiferous tubules was observed at rMIF concentrations ranging from 10-100 ng/ml. Taken together, these data indicate that Leydig cells produce MIF in vivo and suggest an important regulatory role for this newly discovered mediator of testicular function.

Animals↗
PubMed1992

Cell-, age- and stage-dependent distribution of connexin43 gap junctions in testes.

Immunocytochemical data demonstrate that the distribution of gap junction connexin43 (Cx43) in rodent testes is dependent on cell type, testis maturation, and stage of the mature seminiferous epithelium. Western blotting and indirect immunofluorescence microscopy using anti-peptide antisera to Cx43 revealed abundant Cx43 in rat and mouse testes and mouse TM3 and TM4 cells. Cx43 mRNA was detected in rat testes and mouse TM4 cells by Northern blot analysis. Cx43 was localized by immunogold electron microscopy to gap junctions on Sertoli cells and Leydig cells. A punctate distribution of Cx43 was observed on peritubular cell surfaces following indirect immunofluorescence of detergent-permeabilized tubule segments. In cryosections from testes of immature (to 30 days) rats, and mature rats and mice, Leydig cells showed a punctate surface distribution of Cx43 following indirect immunofluorescence. A diffuse cytoplasmic fluorescence was also seen in spermatocytes and spermatogonia. Cx43 staining associated with Sertoli cells was age- and stage-dependent. Over 90% of the tubules in immature tests (22-30 days) contained Cx43 in the region of Sertoli-Sertoli occluding junctions and in the adluminal compartment. In mature rat testes, however, Cx43 immunostaining was detected in only 60% of 1195 tubule sections where it was abundant proximal to the Sertoli cell occluding junctions. All strongly stained tubules were from stages I-VIII, while negatively stained tubules were at stages IX-XIV. Cx43 immunostaining in mature mouse testes was also stage-dependent with all positive tubules at stages VI-VIII. In contrast to Cx43, Cx26 and Cx32 were detected by immunofluorescence only in the apical regions of the seminiferous epithelia in 90% of tubules from mature rats. Consistent with the observed Cx43 immunostaining, octanol-sensitive in situ dye-coupling was observed between Leydig cells, between peritubular cells and between Sertoli cells, suggesting the occurrence of functional gap junctions in these cell types. These observations provide evidence for extensive gap junction-mediated communication between a variety of testis cell types important to the support of spermatogenesis.

Animals↗
PubMed2004

[A molecular basis for odorant recognition: olfactory receptor pharmacology].

Olfactory receptors (ORs) comprise the largest super-family of rhodopsin-like G-protein coupled receptors (GPCR) that involve the recognition and discrimination of thousands of odorants. We recently succeeded in functional reconstitution of mouse ORs in mammalian cell lines and provided molecular evidence that structurally-related ORs recognized overlapping sets of odorants with distinct ligand specificities. Here we show that mOR-EG, a mouse olfactory receptor that was isolated from a eugenol-responsive cell, recognizes 22 different odorants with EC50 values ranging from a few microM to several hundred microM. We constructed a molecular model of mOR-EG using the recent atomic-level structure of bovine rhodopsin. Site-directed mutations were introduced in a potential ligand-binding pocket based on computational ligand-docking simulation. Mutations of some amino acid residues in TM3, TM5, and TM6 dramatically affected the EC50 value of eugenol in Ca2+ imaging. Finally, we succeeded in rational receptor design with predicted ligand specificity by introducing point mutations in the binding site, confirming the accuracy of the binding site mapping. The current studies also help understand mechanisms underlying molecular recognition by GPCRs, with implications for therapeutic application.

Animals↗
PubMed2004

Modeling the distributed gain of single--(1050 or 1410 nm) and dual-wavelength--(800 + 1050 nm or 800 + 1410 nm) pumped thulium-doped fiber amplifiers.

The distributed gain of single- and dual-wavelength-pumped thulium-doped fiber amplifiers is modeled. The excellent agreement between the model and coherent optical frequency domain reflectometry measurements enables us to estimate intrinsic loss, branching ratios of fluorescence originating from the 3H4 level, and cross sections of upconversion pumping at 1050 and 1410 nm for the Tm3+ ions in the fiber. With the branching ratios obtained it is possible to describe induced signal absorption when pumping at 800 nm.

Journal Article↗
PubMed2005

Spectral hole burning for wideband, high-resolution radio-frequency spectrum analysis.

We present experimental results for what is to our knowledge the first spectral-hole-burning based rf spectrum analyzer to cover 10 GHz of rf analysis bandwidth. The rf signal of interest is modulated onto an optical carrier, and the resultant optical sidebands are burned into the inhomogeneously broadened absorption band of a Tm3+:YAG crystal. At the same time a second, frequency-swept laser reads out the absorption profile, which is a double-sideband replica of the rf spectrum, and thus the rf spectrum can be deduced after spectral calibration of the nonlinear readout chirp. This initial demonstration shows spectral analysis covering 10 GHz of bandwidth with >5500 spectral channels and provides 43 dB of dynamic range.

Journal Article↗
PubMed2007

High-power 83 W holmium-doped silica fiber laser operating with high beam quality.

A high-power 83 W cladding-pumped Tm3+-Ho3+-doped silica fiber laser is reported. Using bidirectional 793 nm diode pumping, a maximum slope efficiency of 42% was produced after a threshold launched pump power of 12 W was exceeded. The laser operated at wavelengths near 2105 nm with moderate beam quality, i.e., M2 approximately 1.5. Further power scaling of the fiber laser was limited by thermal failure of the fiber ends.

Journal Article↗
PubMed1988

Effects of BAYm 1099, new alpha-glucosidase inhibitor, on acute metabolic responses and metabolic control in NIDDM over 1 mo.

To examine the clinical role of BAYm 1099, 15 diet-treated non-insulin-dependent diabetic (NIDDM) subjects were randomized to start drug (50 mg 3 times/day) or placebo after a 4-wk run-in period in a double-blind crossover study. Treatment periods (4 wk) were separated by a 2-wk washout period. During the last week of each treatment period, three test meals (TMs) were administered: 60 g starch (TM1), 25 g sucrose (TM2), and combined 60 g starch and 25 g sucrose (TM3). Twelve subjects completed the study. The peak postprandial blood glucose, lactate, and pyruvate levels (means +/- SE) were significantly lower with active drug after all test meals, particularly TM2 (11.3 +/- 1.0 vs. 14.3 +/- 1.4 mM, P less than .001; 1.53 +/- 0.20 vs. 2.48 +/- 0.17 mM, P less than .001; and 105.1 +/- 17.6 vs. 147.6 +/- 11.1 microM, P less than) less than .001; and 105.1 +/- 17.6 vs. 147.6 +/- 11.1 microM, P less than .05, respectively. Peak blood glucose levels were significantly delayed. However, fasting blood glucose, HbA1, fructosamine, and cholesterol did not change during active treatment (10.0 +/- 1.0 vs. 9.9 +/- 1.0 mM, 10.0 +/- 0.7 vs. 9.4 +/- 0.7%, 2.44 +/- 0.10 vs. 2.37 +/- 0.07 mmol/100 g protein, and 6.7 +/- 0.3 vs. 6.5 +/- 0.3 mM, P NS). Flatulence and diarrhea were severe in 2 subjects, requiring termination of study. Thus, in NIDDM, BAYm 1099 was effective in diminishing and delaying postprandial excursions of blood glucose, lactate, and pyruvate after high- and low-sucrose meals, but overall metabolic control remained unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

1-Deoxynojirimycin↗
PubMed2001

The biphasic stimulation of proliferation of Leydig cells by estrogen exposure.

In this study, we have examined the influence of diethylstilbestrol (DES) and 17 beta-estradiol on the proliferation of TM3 Leydig cells, a normalized mouse cell line. Cells were treated with seven different concentrations (1 pg-1 microg/ml) of DES or 17 beta-estradiol, and cell growth was measured at 24-, 48-, and 72-h periods. DES treatment resulted in a significant (p<0.05) stimulation of cell proliferation. We observed two independent peaks of cell proliferation, one at 1 pg/ml DES (186.87%) and the other at 100 ng/ml DES (248.23%). Cytotoxicity was noted at all time periods with 1 microg/ml DES treatment. 17 beta-estradiol treatment resulted in a significant stimulation of cell proliferation (p<0.05) with a trend similar in response to that of DES treatment, as peak proliferation was noted with 1 pg/ml 17 beta-estradiol (125.27%) and 10 ng/ml 17 beta-estradiol (138.31%). Based on these data, it appears that DES is more mitogenic in these Leydig cells compared to 17 beta-estradiol. Furthermore, for the first time, we detected that both DES and 17 beta-estradiol were able to stimulate proliferation of Leydig cells in a biphasic fashion. Cell cycle kinetic analysis revealed that cell entry into the S-phase was higher in the DES treated cells compared to the controls, and doubling times of DES exposed cells were significantly reduced (p<0.05). Co-administration of tamoxifen at a concentration 1000-fold higher than either DES or 17 beta-estradiol resulted in complete inhibition of cell proliferation. Analysis of expression of ER alpha and ER beta by RT-PCR in untreated Leydig cells, as well as Leydig cells exposed to 1 pg/ml DES, revealed that the transcripts of ER alpha and ER beta were not detectable even after 40 cycles of amplification. A 100-ng/ml dose of DES induced ER alpha expression by 20-fold. These data suggest that estrogen exposure-mediated increases in cell proliferation, coupled with the decrease in cell cycle time, may allow greater accumulation of DNA damage to occur in the testicular target cells compared to untreated cells under normal cell cycle control. In addition, an unidentified estrogen receptor may be responsible for the mitogenic activity of estrogens at low levels.

Animals↗
PubMed1999

Molecular properties and signalling pathways of the histamine H1 receptor.

With cloning of the gene encoding the histamine H1 receptor, a new area of histamine research has become reality. Finally, it seems feasible to study the target of the therapeutically important clans of antihistamine. Expression of the genes in mammalian cells allows detailed investigations of the various signal transduction routes of the histamine H1 receptor. Moreover, using molecular biological techniques, it is now possible to investigate ligand receptor interaction at the molecular level. Studies with mutant H1 receptors have shown that H1 antagonists bind to a specific amino acid residues in TM3 and 5. It is expected that these new developments will provide much fundamental knowledge on the ligand interaction with the H1 receptor.

Amino Acid Sequence↗
PubMed1999

Molecular modeling of the oxytocin receptor/bioligand interactions.

Oxytocin is a nonapeptide hormone (CYIQNCPLG-NH2, OT), controlling labor and lactation in mammalian females, via interactions with specific cellular membrane receptors (OTRs). The native hormone is cyclized via a 1-6 disulfide and its receptor belongs to the GTP-binding (G) protein-coupled receptor (GPCR) family, also known as heptahelical transmembrane (7TM) or serpentine receptors. Using a technique combining multiple sequence alignments with available experimental constraints, a reliable OTR model was built. Subsequently, the OTR complexes with a selective agonist [Thr4,Gly7]OT, a selective cyclohexapeptide antagonist L-366,948 and oxytocin itself were modeled and relaxed using a constrained simulated annealing (CSA) protocol. All three ligands seem to prefer similar modes of binding to the receptor, manifested by repeating receptor residues which directly interact with the ligands. Those involved in the three complexes are putative helices: TM3: R113, K116, Q119, M123; TM4: Q171, and TM5: I201 and T205. Most of them are the equivalent residues/positions to those found in our earlier studies, regarding related vasopressin V2 receptor/bioligand interactions.

Amino Acid Sequence↗
PubMedDate not supplied

Identification and regulation of receptor tyrosine kinases Rse and Mer and their ligand Gas6 in testicular somatic cells.

Receptor tyrosine kinases act to convey extracellular signals to intracellular signaling pathways and ultimately control cell proliferation and differentiation. Rse, Axl, and Mer belong to a newly identified family of cell adhesion molecule-related receptor tyrosine kinase. They bind the vitamin K-dependent protein growth arrest-specific gene 6 (Gas6), which is also structurally related to the anticoagulation factor Protein S. The aim of this study is to investigate the possible role of Rse/Axl/Mer tyrosine kinase receptors and their ligand in regulating testicular functions. Gene expression of Rse, Axl, Mer, and Gas6 in the testis was studied by reverse transcriptase-polymerase chain reaction (RT-PCR) and Northern blot analysis. The results indicated that receptors Rse and Mer and the ligand Gas6 were expressed in the rat endothelial cell line (TR1), mouse Leydig cell line (TM3), rat peritubular myoid cell line (TRM), mouse Sertoli cell line (TM4), and primary rat Sertoli cells. Axl was not expressed in the testicular somatic cells by RT-PCR or Northern blot analysis. The highest level of expression of Gas6 messenger RNA (mRNA) was observed in the Sertoli cells, and its expression was responsive to the addition of forskolin in vitro. The effects of serum, insulin, and transferrin on Gas6 expression by TM4 cells were examined. It was shown that they all exhibited an up-regulating effect on Gas6 expression. The forskolin-stimulated Gas6 expression was accompanied by an increase in tyrosine phosphorylation of the Rse receptor in vitro, suggesting that Gas6 may exhibit an autocrine effect in the Sertoli cells through multiple tyrosine kinase receptors. Our studies so far have demonstrated that tyrosine kinase receptors Rse and Mer and their ligand Gas6 are widely expressed in the testicular somatic cell lines and may play a marked role in promoting testicular cell survival.

Animals↗
PubMed2000

[Study on unsupervised classification in marshland of endemic area of Schistosomiasis Japonica using satellite TM image data].

OBJECTIVE: To categorize the vegetation of marshland in the endemic areas of Schistosomiasis Japonica using satellite thematic mapper (TM)data in Liupo Village, Anhui Province. METHODS: Data of three satellite TM hands, namely TM3, TM4 and TM5, were selected to be used in classification with principal component analysis. Then, satellite TM images were applied to false color composite and unsupervised classification with computer software to manage the images. Finally, the resulting clusters were identified and reclassified by site visits to categorize the land coverage and vegetation. RESULTS: Five classifications of land coverage were generated, including poplar forest, bulrush and marshland, all with snail habitants. Based on the survey in the spring of 1998, the overall live snail density and infested snail density in the study areas were 0.510/0.11 m2 and 0.007/0.11 m2, respectively. CONCLUSION: Unsupervised classification, which is a technique for the interpretation of remotely sensed imagery, can contribute to the classification of environment with snail habitants and ecological diseases and become a new method in epidemiological studies.

Animals↗
PubMed2000

Building 3D-structural model of kappa opioid receptor and studying its interaction mechanism with dynorphin A(1-8).

AIM: To construct the 3D-structural model of human kappa opioid receptor (HKOR) and study its interacting mechanism with dynorphin A(1-8) (Dyn8). METHODS: Comparative molecular modeling was applied to build the 7 transmembrane (TM) helical domain of HKOR using the bovine rhodopsin (OPSD) model as a template. Molecular dynamics was performed to minimize the HKOR model and to simulate the 3D-structure of Dyn8 based on the NMR results of dynorphin A(1-14). The extracellular loops (EL) were built by self-constructed database searching. DOCK4.0 program was performed to construct Dyn8 complex with HKOR. RESULTS: (1) The model of HKOR was obtained and validated by theoretical and experimental data. (2) The Dyn8-HKOR interacting mechanism is reasonably explained: Side chain of residue Asp138 interacts with protonated nitrogen atom at the N-terminal residues of Dyn8 through electrostatic and hydrogen bonding, which play an important role in ligand binding with receptor. (3) Negatively charged amino acids in the second extracellular loop (EL2) as Asp223 and Glu209 interact with the C-terminal positively charged residues in Dyn8, and Glu209 is a likely determinant of peptide ligand specificity. CONCLUSION: Some amino acid residues positioned in EL2, TM3, TM4, and TM5 form the binding site and therefore determine the selectivity of kappa peptide agonist.

Amino Acid Sequence↗
PubMed2001

[Classification study on the marshland in endemic areas of Schistosoma japonicum using satellite TM image data].

OBJECTIVE: To create a land cover map of the marshland region of Schistosoma Japonicum using satellite TM data from Chayegang, Jiangxi Province. METHODS: Satellite data of three TM bands, namely TM3, TM4 and TM5, were selected to be used in classification study with Principal Components Analysis. Then TM satellite images were applied to false color composite and unsupervised classification with computer software to manage the TM data. Finally the resulting clusters were identified by undertaking site visits and a systematic sampling snail survey was also carried out in the study area in April, 2000. RESULTS: Three land cover classes were generated, including class 1, the carex zone that is both the dominant vegetation and main snail habitats of the study area. Based on the snail survey in the spring of 2000, the live snail density and infectious snail density of the carex zone were 2.51/0.11 m2 and 0.006 9/0.11 m2, respectively. The infection rate of the snail was 0.28%. No snail was found in land cover class 3, the mixed vegetation, because the altitude of this area is either above 17 m or under 14 m and therefore the vegetation in this area is unsuitable for snails to survive. CONCLUSION: Remote sensing can contribute the study on the distribution of snail habitats and become a promising epidemiological study method for schistosomiasis and other ecological diseases.

Animals↗