Evaluation of the economic and environmental impact of converting cropland to forest: a case study in Dunhua county, China

The Sloping Land Conversion Program (also known as "Grain for Green" or the Upland Conversion Program) for converting cropland to forest is one of China's most ambitious environmental initiatives, and is one of the world's largest land-conservation programs with a budget of RMB 337 billion (over US$ 40 billion). Although environmental impacts have played a vital role in the general reasoning and argumentation for forest plantations, environmental impact analyses have often received less attention than economic analyses in the planning of plantation forestry projects. The overall goal of this paper is to evaluate the program's environmental impact considering the farmer's interests and the potential social benefits due to carbon sequestration in different scenarios based on household and field survey data in Dunhua County. Our findings are that: (1) in many cases, the program did not give adequate consideration to land productivity and environmental heterogeneity when selecting plots; (2) more than half of the reforestation plots were on flat cropland (slopes of less than 5 degrees ); (3) in five of the eight townships, net incomes on reforested land were substantially above or below previous crop incomes, raising questions about the efficiency of the allocation of compensation to farmers participating in the program; (4) the potential carbon co-benefit increased the NPV of the program by 5954-7009 RMB/ha. In conclusion, we recommend that more attention should be paid to the quality of reforestation programs rather than just their scale and note that consideration of potential carbon sequestration co-benefits enhances the benefits of cropland conversion programs.

Segmental bone tissue engineering by seeding osteoblast precursor cells into titanium mesh-coral composite scaffolds

The size and specific shape of bone grafts are important for jaw reconstruction. In this experiment, segmental bone grafts were engineered in a predetermined shape via seeding osteoblast precursor cells into titanium mesh-coral composite scaffolds. Titanium meshes were moulded into the shape of a column with length 12 mm and diameter 8mm. The column was filled with natural coral granules and the complex acted as a cell-seeding scaffold. About 4 x 10(7) osteoblast precursor cells in 200 microl cell-culture medium were seeded into each of six scaffolds and incubated in vitro for 2 days. Then, the composites were implanted subcutaneously into the backs of nude mice and incubated in vivo. Two months after implantation, the animals were killed and new bone formed in the scaffolds was investigated by gross inspection, X-ray examination, histological observation and mechanical testing. The results showed that newly formed tissue was red and presented the gross appearance of bone, and kept the original shape of the column. Titanium mesh was situated on the surface of the bone graft. An X-ray blocking shadow was observed in and around the titanium scaffolds; most of the coral granules had been absorbed. Histological observation demonstrated a large amount of new bone formed and integrated well with titanium mesh. Mechanical testing showed that new bone improved the mechanical property of the graft significantly. In conclusion, a titanium mesh-coral composite scaffold with osteoblast precursor cells is an efficient means to engineer segmental bone, possessing the desired shape and mechanical strength.

Exchange bias dependence on interface spin alignment in a Ni80Fe20/(Ni,Fe)O thin film

A Ni80Fe20/(Ni,Fe)O thin film exhibits a positive exchange bias when cooled in a zero field and a negative exchange bias when field cooled. With transmission electron microscopy and electron energy loss spectrometry, the composition and magnetic structure has been ascertained and a distribution of magnetization easy axes about the interface extrapolated. The results indicate that the positive exchange bias is from antiferromagnetic interface moments perpendicular to their ferromagnetic counterparts. With field cooling the alignment is put into a parallel configuration resulting in a negative exchange bias.

Tuning the exchange bias in NiFe/Fe-oxide bilayers by way of different Fe-oxide based mixtures made with an ion-beam deposition technique

We have investigated the structural and magnetic properties of ion-beam deposited polycrystalline NiFe (25 nm)/Fe-oxide (35 nm) bilayers. A film prepared with an assist beam O2 to Ar gas ratio of 0% during deposition had a bottom layer that consisted of pure b.c.c. Fe (a = 2.87 A) whereas films prepared with 19%O2/Ar and 35%O2/Ar had either Fe3O4 (a = 8.47 angstroms) or alpha-Fe2O3 (a = 5.04 angstroms, c = 13.86 angstroms) bottom layers, respectively. Cross-sectional transmission electron microscopy revealed a smooth interface between the top nano-columnar NiFe and bottom nano-columnar Fe-oxide layer for all films. At room temperature, the observed coercivity (Hc approximately 25 Oe) for a film prepared with 19% O2/Ar indicates the existence of a magnetically hard ferrimagnetic Fe3O4 phase that is enhancing the plain NiFe (Hc approximately 2 Oe) by way of exchange coupling. A significant amount of exchange bias is observed below 50 K, and at 10 K the size of exchange bias hysteresis loops shift increases with increasing oxygen in the films. Furthermore, the strongest exchange coupling (H(ex) approximately 135 Oe at 10 K) is with alpha-Fe2O3 (35% O2/Ar) as the bottom film layer. This indicates that the pure antiferromagnetic phases work better than ferrimagnetic phases when in contact with ferromagnetic NiFe. H(ex) (T) is well described by an effective AF domain wall energy that creates an exchange field with a (1 - T/T(crit)) temperature dependence. Hc (T) exhibits three distinct regimes of constant temperature that may indicate the existence of different AF spin populations that couple to the FM layer at different temperatures.

Compliance with DOTS diagnosis and treatment recommendations by private practitioners in Kerala, India

The Indian government has a national tuberculosis (TB) plan based on DOTS recommendations. The private health sector plays an increasing role in health care provision in India, and a public-private mix (PPM) project has been introduced to standardise TB diagnosis and treatment methods in Kerala, India. This study interviewed 45 private practitioners (PPs) to evaluate diagnostic, treatment and reporting practices, of whom 80% diagnose with sputum microscopy and 43% treat all of their patients according to the treatment regimens recommended by the DOTS strategy. This study demonstrates that the current management of TB by private practitioners in Kerala is still in need of improvement.

Development of gastric slow waves and effects of feeding in pre-term and full-term infants

The aims of this study were to investigate the difference in developmental process of gastric slow waves and the effects of feeding in pre-term and full-term infants. Twenty-six pre-term and 31 full-term infants were enrolled in the study. Gastric myoelectrical activity was recorded using electrogastrography (EGG) from birth to month 6. An increase in the % of 2-4 cpm slow waves was noted in both pre-term (P < 0.01) and full-term infants (P < 0.04) from birth to month 4. The pre-term infants showed a reduced dominant EGG power at certain points of the study. (3) Breast or formula feeding resulted in no difference in the EGG in the full-term infants and showed a difference in the postprandial dominant power of the EGG in the pre-term infants only at month 2 after birth (P < 0.05) but not at other times. The gastric slow wave in pre-term infants is of a significantly reduced amplitude but similar rhythmicity. The method of feeding has no effects on the EGG in full-term infants and minimal effects (may be of non-clinical significance) on the EGG in pre-term infants as the difference was noted only at one time point during the 6-month follow-up study.

Characterization of a Novel Polymeric Scaffold for Potential Application in Tendon/Ligament Tissue Engineering

Unlike braided fabrics, knitted scaffolds have been proven to favor deposition of collagenous connective tissue matrix, which is crucial for tendon/ligament reconstruction. But cell seeding of such scaffolds often requires a gel system, which is unstable in a dynamic situation, especially in the knee joint. This study developed a novel, biodegradable nano-microfibrous polymer scaffold by electrospinning PLGA nanofibers onto a knitted PLGA scaffold in order to provide a large biomimetic surface for cell attachment. Porcine bone marrow stromal cells were seeded onto either the novel scaffolds by pipetting a cell suspension (Group I) or the knitted PLGA scaffolds by immobilizing in fibrin gel (Group II). Cell attachment at 36 hours, cell proliferation and extracellular matrix synthesis at 1 week, and mechanical properties over 2 weeks were investigated. Cell attachment was comparable and cell proliferation was faster in Group I. Moreover, cellular function was more actively exhibited in Group I, as evident by the higher expression of collagen I, decorin, and biglycan genes. Thus, this novel scaffold, facilitating cell seeding and promoting cell proliferation, function, and differentiation, could be applied with promise in tissue engineering of tendon/ligament.

Tachygastria induced by gastric electrical stimulation is mediated via alpha- and beta-adrenergic pathway and inhibits antral motility in dogs

BACKGROUND

It is known that tachygastria is associated with gastric hypomotility and retrograde gastric electrical stimulation (RGES) delays gastric emptying and is proposed for treating obesity. The aim was to investigate the effects and mechanisms of RGES on postprandial antral contraction in dogs.

METHODS

Seven dogs were implanted with a gastric cannula and three pairs of gastric serosal electrodes. Antral contractions and gastric myoelectrical activity were recorded immediately after a solid meal, with or without RGES, or with GES on the corpus, or with RGES under administration of propranolol. The stimulus was composed of long pulses with a tachygastrial frequency.

RESULTS

(i) GES at the tachygastrial frequency impaired gastric myoelectrical activity and induced tachygastria (anovaP<0.05). (ii) GES at the tachygastrial frequency suppressed antral contractions (anovaP<0.01) and the effect was stronger with retrograde stimulation than forward stimulation (P<0.05). (iii) GES-induced tachygastria was correlated with antral hypomotility (r=-0.60, P=0.01). (iv) Propranolol and phentolamine abolished GES-induced tachygastria and antral hypomotility.

CONCLUSIONS

Long-pulse RGES at a tachygastrial frequency suppresses postprandial antral contractions, which is attributed to an induction of tachygastria via the alpha- and beta-adrenergic pathway.

Assessment of gastric volume changes with sonometry compared with barostat

AIM

The aim was to investigate the validity of sonometry on the assessment of gastric volumes in comparison with gastric barostat.

METHOD

Six dogs were implanted with gastric serosal electrodes, sonometric sensors, and a gastric cannula. Experiments were performed to assess sensor distance when an intragastric balloon was inflated with different volumes, after a meal with or without a balloon, and with gastric electrical stimulation.

RESULTS

(i) The distance measured using sonometry was reproducible and stable, and there was a correlation between sensor distance and the gastric volume measured with barostat. (ii) Simultaneous recordings by sonometry and barostat showed a similar postprandial response, while the postprandial increase of the sensor distance was much smaller without the balloon (3.2+/-0.2 mm vs 9.7+/-1.5 mm, P<0.02). (iii) The sensor distance was increased with gastric electrical stimulation.

CONCLUSIONS

Sonometry is able to detect gastric volume changes as validated by gastric perturbations with distensions, food ingestion and electrical stimulation. The postprandial increase in gastric volume measured by sonometry with barostat balloon is greater because of the presence of the intragastric balloon.

Review article: therapeutic roles of acupuncture in functional gastrointestinal disorders

Acupuncture has been practiced empirically in China for several millennia, and is being increasingly accepted by practitioners and patients worldwide. Functional gastrointestinal disorders are common in clinical gastroenterology. The prevalence of one or more functional gastrointestinal disorders is estimated to be as high as 70% in general population using Rome diagnostic criteria. Since functional gastrointestinal disorders are diagnosed based on symptoms and the exact aetiologies for most of functional gastrointestinal disorders are not completely known, it is not unusual that the treatment for these disorders is unsatisfactory and alternative therapies are attractive to both patients and practitioners. During the latest decades, a considerable number of studies have been performed on acupuncture for the treatment of functional gastrointestinal disorders and underlying mechanisms. In this article, we reviewed available data in the literature on the applications and mechanisms of acupuncture for the treatment of functional gastrointestinal disorders, including functional oesophageal disorders, nausea and vomiting, functional dyspepsia, irritable bowel syndrome, constipation, etc. A summary is provided based on the quality and quantity of published studies regarding the efficacy of acupuncture in treating these various disorders. In addition, the methodology of acupuncture is also introduced.

Review article: therapeutic roles of acupuncture in functional gastrointestinal disorders

Acupuncture has been practiced empirically in China for several millennia, and is being increasingly accepted by practitioners and patients worldwide. Functional gastrointestinal disorders are common in clinical gastroenterology. The prevalence of one or more functional gastrointestinal disorders is estimated to be as high as 70% in general population using Rome diagnostic criteria. Since functional gastrointestinal disorders are diagnosed based on symptoms and the exact aetiologies for most of functional gastrointestinal disorders are not completely known, it is not unusual that the treatment for these disorders is unsatisfactory and alternative therapies are attractive to both patients and practitioners. During the latest decades, a considerable number of studies have been performed on acupuncture for the treatment of functional gastrointestinal disorders and underlying mechanisms. In this article, we reviewed available data in the literature on the applications and mechanisms of acupuncture for the treatment of functional gastrointestinal disorders, including functional oesophageal disorders, nausea and vomiting, functional dyspepsia, irritable bowel syndrome, constipation, etc. A summary is provided based on the quality and quantity of published studies regarding the efficacy of acupuncture in treating these various disorders. In addition, the methodology of acupuncture is also introduced.

Effects of gastric electrical field stimulation with long pulses on gastric emptying in dogs

The aim was to investigate the effects of electrical field stimulation (EFS) with long and short pulses on gastric emptying, gastric contractility and vagal activity in dogs. Sixteen dogs were equipped with a duodenal cannula, electrodes and strain gauges (10 dogs) in the stomach. Each dog was fed with Ensure and gastric effluent was collected from the cannula. Electrical stimulation was applied via two electrodes (about 12 cm apart, one in the corpus and the other in the antrum) with long pulses (a frequency of 6 cycles min-1, pulse amplitude of 6 mA and width of 100 ms) in 10 dogs and with short pulses (frequency of 30 Hz and pulse width of 300 micros) in six dogs. The electrocardiogram was also recorded and heart rate variability was derived to assess the vagal activity. It was found that: (i). EFS with long pulses did not alter gastric emptying during stimulation but increased gastric emptying during the 45 min immediately after stimulation; (ii). EFS with long pulses increased gastric contractility in both proximal and distal antrum during and after the stimulation; (iii). EFS with long pulses resulted in an increase in vagal tone during the 45 min immediately after stimulation. However, there is no difference during the 45 min period of stimulation; (iv). EFS with short pulses had no effect on gastric emptying. We concluded that long pulse gastric electrical field stimulation with one electrode in the corpus and the other electrode in the antrum has postponed effects on gastric emptying of liquid, gastric contractility and vagal activity.

Synthesis and conformational analysis of a coumarinic acid-based cyclic prodrug of an opioid peptide with modified sensitivity to esterase-catalyzed bioconversion

The coumarinic acid-based cyclic DADLE (H-Tyr-D-Ala-Gly-Phe-D-Leu-OH) prodrug 1a exhibited more favorable physicochemical properties than did DADLE for permeation across the intestinal mucosa. However, prodrug 1a, whose bioconversion to DADLE was slow, was subject to extensive biliary clearance when administered to rats in vivo. To increase the rate of esterase-catalyzed bioconversion of prodrug 1a, thus decreasing its biliary clearance, the oxymethyl-modified prodrug 1, in which an aldehyde equivalent is inserted between the phenolic group of the promoiety and the carboxylic acid group of the peptide, was synthesized from benzofuran-2-carboxylic acid 16 via a nine-step procedure. Briefly, phenacyl-protected 3-(2-hydroxyphenyl)-propynoic acid 17 was coupled with Boc-d-Leu-OCH(2)I 5 to give the intermediate 18, which was further elaborated and conjugated with tetrapeptide 4 to give linear precursor 2. Precursor 2 was then deprotected and cyclized to obtain compound 1 using a high dilution technique. In an attempt to investigate the effect of the physicochemical properties and the conformation of prodrug 1 on its permeation characteristics, we calculated its physicochemical parameters and determined its solution conformation using spectroscopic techniques (CD and NMR) and molecular dynamics simulations. Prodrug 1 showed a cLogP value and a molecular size similar to that of prodrug 1a. The deconvoluted CD spectra indicated that prodrug 1 has more random component (71%) than prodrug 1a (42%). 2D-NMR studies of prodrug 1 showed no signals for amide-amide hydrogen interactions and few ROE cross-peaks in ROESY spectra. Using distance restraints constructed from ROESY spectra, molecular dynamics simulations of prodrug 1 generated five conformation families. One family satisfied most of the distance restraints and all of the dihedral angles measured by NMR coupling constants. In summary, prodrug 1 showed favorable physicochemical properties for permeation of the intestinal mucosa. Prodrug 1 adopted a more random conformation in solution than prodrug 1a. These differences in solution conformation could affect the permeation of the prodrugs across the intestinal mucosa by passive diffusion and/or their ability to interact with efflux transporter(s) that would limit their transcellular permeation.

[Heat transfer analysis of liquid cooling garment used for extravehicular activity]

Brief description was given about the construction and function of the LCG (liquid cooling garment) used for EVA (extravehicular activity). The heat convection was analyzed between ventilating gas and LCG, the heat and mass transfer process was analyzed too, then a heat and mass transfer mathematical model of LCG was developed. Thermal physiological experimental study with human body wearing LVCG (liquid cooling and ventilation garment) used for EVA was carried out to verify this mathematical model. This study provided a basis for the design of liquid-cooling and ventilation system for the space suit.

Matrix gamma-carboxyglutamic acid protein is a key regulator of PTH-mediated inhibition of mineralization in MC3T3-E1 osteoblast-like cells

As part of its overall function as a major regulator of calcium homeostasis, PTH stimulates bone resorption and inhibits osteoblast-mediated biomineralization. To determine the basis for the inhibitory actions of this hormone, we compared the time course of PTH-dependent inhibition of mineralization in MC3T3-E1 osteoblast-like cells with changes in mRNA levels for several extracellular matrix proteins previously associated either with induction or inhibition of mineralization. Mineralizing activity was rapidly lost in PTH-treated cells ( approximately 30% inhibition after 3 h, 50% inhibition at 6 h). Of the proteins examined, changes in matrix gamma-carboxyglutamic acid protein were best correlated with PTH-dependent inhibition of mineralization. Matrix gamma-carboxyglutamic acid protein mRNA was rapidly induced 3 h after PTH treatment, with a 6- to 8-fold induction seen after 6 h. Local in vivo injection of PTH over the calvaria of mice also induced a 2-fold increase in matrix gamma-carboxyglutamic acid protein mRNA. Warfarin, an inhibitor of matrix gamma-carboxyglutamic acid protein gamma-carboxylation, reversed the effects of PTH on mineralization in MC3T3-E1 cells, whereas vitamin K enhanced PTH activity, as would be expected if a gamma-carboxyglutamic acid-containing protein were required for PTH activity. Levels of the other mRNAs examined were not well correlated with the observed changes in mineralization. Osteopontin, an in vitro inhibitor of mineralization, was induced approximately 4-fold 12 h after PTH addition. Bone sialoprotein mRNA, which encodes an extracellular matrix component most frequently associated with mineral induction, was inhibited by 50% after 12 h of PTH treatment. Osteocalcin mRNA, encoding the other known gamma-carboxyglutamic acid protein in bone, was also inhibited by PTH, but, again, with a significantly slower time course than was seen for mineral inhibition. Taken together, these results show that the rapid inhibition of osteoblast mineralization induced by in vitro PTH treatment is at least in part explained by induction of matrix gamma-carboxyglutamic acid protein.

[Influence of temperature and moisture on soil nitrogen mineralization under two types of forest in Changbai Mountain]

The effect of temperature(t) and soil water content(theta) on soil nitrogen mineralization under coniferous-broadleaved and spruce-fir coniferous forests was evaluated by using laboratory incubation method. Based on the analysis of inorganic nitrogen in soil extracts before and after incubation, it was showed that the net mineralization rate of soil nitrogen was positively related to t(alpha < 0.001) from 5 degrees C to 35 degrees C, and to water content when water contents was low, but there was a decrease in net mineralization rate when the water content was above an optimum value. The result suggested the interactive effect of temperature and moisture on the mineralization of soil nitrogen. Two dimensional (t, theta) equations to describe the effect were drawn up.

Nuclear factor-kappa B-inducible death effector domain-containing protein suppresses tumor necrosis factor-mediated apoptosis by inhibiting caspase-8 activity

Activation of the transcription factor nuclear factor-kappa B (NF-kappa B) has been found to play an essential role in the inhibition of tumor necrosis factor (TNF)-mediated apoptosis. NF-kappa B regulates several antiapoptotic molecules including inhibitors of apoptosis, Bcl-2 family proteins (A1 and Bcl-X(L))(,) and IEX-IL. Here we report that the expression of a small death effector domain (DED)-containing protein, NDED (NF-kappa B-inducible DED-containing protein), depends on the activation of NF-kappa B. The inhibition of NF-kappa B by I kappa B alpha, a natural inhibitor of NF-kappa B, suppressed NDED mRNA expression induced by TNF. The restoration of NDED in NF-kappa B null cells inhibited TNF-induced apoptosis. Intriguingly, unlike the caspase-8 inhibitor cellular FADD-like interleukin-1 beta converting enzyme-inhibitory protein (c-FLIP), NDED suppressed TNF-mediated apoptosis by inhibiting TNF-induced caspase-8 enzymatic activity but not the processing of caspase-8. Furthermore, NDED could not inhibit etoposide-mediated apoptosis that is independent of caspase-8 activation. Our results provide the first demonstration that NF-kappa B transcriptionally induces the DED-containing protein to suppress TNF-mediated apoptosis by inhibiting caspase-8 activity, which offers new insight into the antiapoptotic mechanism of NF-kappa B.

[Clinical study on effect of zhuhuang granule no. 2 in treating psoriasis with liver-qi stagnancy]

OBJECTIVE

To observe the efficacy of Zhuhuang Granule No. 2 (ZHG2) in treating psoriasis with Liver-Qi stagnancy.

METHODS

Sixty-seven patients were randomly divided into two groups, the 33 patients in the control group were treated with composite indigo capsule and the 34 in the treated group treated with ZHG2, and the clinical effect, changes of main symptoms and local skin lesion after treatment were evaluated. Meanwhile, the plasma levels of substance P (SP) and vasoactive intestinal peptide (VIP) in 15 patients and 13 healthy subjects were measured using radioimmunoassay (RIA).

RESULTS

The total effective rate in the treated group and the control group was 97.1% and 78.8% respectively with significant difference, P < 0.05. ZHG2 showed a significant effect in reducing plasma level of SP and VIP in patients of psoriasis with Liver-Qi stagnancy.

CONCLUSION

The effect of ZHG2 in treating psoriasis patients with Liver-Qi stagnancy is satisfactory, and worth further studying.

ATM is required for IkappaB kinase (IKKk) activation in response to DNA double strand breaks

Following challenge with proinflammatory stimuli or generation of DNA double strand breaks (DSBs), transcription factor NF-kappaB translocates from the cytoplasm to the nucleus to activate expression of target genes. In addition, NF-kappaB plays a key role in protecting cells from proapoptotic stimuli, including DSBs. Patients suffering from the genetic disorder ataxia-telangiectasia, caused by mutations in the ATM gene, are highly sensitive to inducers of DSBs, such as ionizing radiation. Similar hypersensitivity is displayed by cell lines derived from ataxia-telangiectasia patients or Atm knockout mice. The ATM protein, a member of the phosphatidylinositol 3-kinase (PI3K)-like family, is a multifunctional protein kinase whose activity is stimulated by DSBs. As both ATM and NF-kappaB deficiencies result in increased sensitivity to DSBs, we examined the role of ATM in NF-kappaB activation. We report that ATM is essential for NF-kappaB activation in response to DSBs but not proinflammatory stimuli, and this activity is mediated via the IkappaB kinase complex. DNA-dependent protein kinase, another member of the PI3K-like family, PI3K itself, and c-Abl, a nuclear tyrosine kinase, are not required for this response.

DNA-PKcs is required for activation of innate immunity by immunostimulatory DNA

Bacterial DNA and related synthetic immunostimulatory oligodeoxyribonucleotides (ISS-ODN) stimulate innate immunity. However, the molecular recognition mechanism that initiates signaling in response to bacterial DNA and ISS-ODN has not been identified. Herein, we demonstrate that administration of bacterial DNA and ISS-ODN to mice lacking the catalytic subunit of DNA-PK (DNA-PKcs) and in vitro stimulation of BMDM from these mice result in defective induction of IL-6 and IL-12. Further analysis using BMDM of IKKbeta(-/-) revealed that both DNA-PKcs and IKKbeta are essential for normal cytokine production in response to ISS-ODN or bacterial DNA. ISS-ODN and bacterial DNA activate DNA-PK, which in turn contributes to activation of IKK and NF-kappaB. These results reveal a novel role of DNA-PKcs in innate immune responses and a link between DNA repair and innate immunity.

[Impacts of forest and precipitation on runoff and sediment in Tianshui watershed and GM models]

This paper analyzed the impacts of foret stand volume and precipitation on annual erosion modulus, mean sediment, maximum sediment, mean runoff, maximum runoff, minimum runoff, mean water level, maximum water level and minimum water level in Tianshui watershed, and also analyzed the effect of the variation of forest stand volume on monthly mean runoff, minimum runoff and mean water level. The dynamic models of grey system GM(1, N) were constructed to simulate the changes of these hydrological elements. The dynamic GM models on the impact of stand volumes of different forest types(Chinese fir, masson pine and broad-leaved forests) with different age classes(young, middle-aged, mature and over-mature) and that of precipitation on the hydrological elements were also constructed, and their changes with time were analyzed.

Parathyroid hormone-related protein down-regulates bone sialoprotein gene expression in cementoblasts: role of the protein kinase A pathway

PTH-related protein (PTHrP) acts as a paracrine and/or autocrine regulator of cell proliferation, apoptosis, and differentiation and is implicated in tooth development. The current studies employed cementoblasts to determine the role(s) and mechanisms of PTHrP in regulating cementum formation. Results demonstrated that PTHrP repressed gene expression and protein synthesis of bone sialoprotein (BSP) and abolished cementoblast-mediated biomineralization in vitro. The BSP gene inhibition required protein synthesis. The PTHrP analog (1-31) and other activators of the PKA pathway (3-isobutyl-1-methylxathine (IBMX), forskolin (FSK) and Sp-Adenosine-3', 5'-cyclic monophosphorothioate (Sp-cAMPss) also down-regulated BSP gene expression and blocked cementoblast-mediated biomineralization. In contrast, the PTHrP analog (7-34), a PTHrP antagonist, and the activators of the PKC pathway [phorbol 12-myristate 13-acetate (PMA) and phorbol 12, 13-dibutyrate (PDBu)] promoted BSP gene expression. In addition, the PKA pathway inhibitor (9-(2-tetrahydrofuryl) adenine (THFA) partially, but significantly reversed the PTHrP-mediated down-regulation of BSP gene expression. Furthermore, THFA alone significantly increased BSP messenger RNA (mRNA) expression in cementoblasts. In contrast, the inhibitor of the PKC pathway (GF109203X) did not reverse the PTHrP inhibitory effect on BSP gene expression. Furthermore, GF109203X alone dramatically reduced the BSP transcript levels. These data indicate that the cAMP/PKA pathway mediates the PTHrP-mediated down-regulation of BSP mRNA expression in cementoblasts; and furthermore, this pathway may, through an intrinsic inhibition mechanism, regulate the basal level of BSP mRNA expression. In contrast, the activation of PKC promotes BSP gene expression. These data provide new insights into the molecular mechanisms involved in PTHrP regulation of cementogenesis.