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Biomedical subjects

P Hou

Publications and source records attributed to P Hou.

At least 19 recordsLinked to original sources
PubMed2006

Response to environmental flows in the Lower Tarim River, Xinjiang, China: an ecological interpretation of water-table dynamics.

Increased water-dependent development and utilization have led to significant environmental and hydrological degradation of the Tarim River in western China and its dependent ecosystems. Between the 1950s and 1970s, 350 km of the lower reaches were drained and between 1960 and 1980 the water-table fell from between -2 and -3 m to between -8 and -10 m. Subsequently, riparian ecosystems were seriously degraded. In 2000, the Chinese government launched a program to restore the lower reaches of the river. Four environmental flows of 1034 x 10(6) m(3) were released from 2000 to 2002. This paper interprets and discusses the ecological significance of changes following the releases and identifies the relationship between water-table dynamics and vegetation responses. Short-term objectives for river restoration are proposed with possible monitoring parameters suggested.

China↗
PubMed2006

Response to environmental flows in the lower Tarim River, Xinjiang, China: ground water.

In China's west since the 1950s large-scale ecosystem degeneration has occurred through water diversions for agricultural purposes. Since 2000, 1038 x 10(6) m(3) of water have been released into the Tarim River with the result that water reached the terminal Taitema Lake for the first time in 30 years. This environmental flow raised water-table levels along 350 km of the river. To assess the response of the water-table, a comparison "pristine" site is compared with downstream monitored sites. The results show huge changes in water-table levels. The study verifies that the water-table is extremely responsive to environmental flows, that strong internal similarities exist along the length of the river, and that the effect on the water-table and hence likely riparian vegetation recovery can be tentatively predicted. The actual impacts of the restoration strategy are less than those originally expected politically, socially and within the scientific community. We make recommendations on more effective release strategies.

China↗
PubMed2006

Diffusion tensor imaging in polymicrogyria: a report of three cases.

INTRODUCTION: Polymicrogyria (PMG), a neuronal migration disorder, commonly manifests as a seizure disorder. The aim of this study was to look for the abnormalities in the underlying white matter using diffusion tensor imaging (DTI) that appeared normal on conventional magnetic resonance imaging (MRI) in patients with PMG. METHODS: DTI was performed in three patients with PMG and eight age- and sex-matched healthy controls. Fractional anisotropy (FA) and mean diffusivity (MD) values were calculated for the cortex and adjoining subcortical white matter in both controls and patients. RESULTS: We observed a significantly decreased mean FA value with no significant change in the MD value in subcortical white matter underlying polymicrogyric cortex (FA = 0.23+/-0.04, MD = 1.0+/-0.05 x 10(-3) mm(2)/s) as compared to both contralateral (FA = 0.32+/-0.04, MD = 1.0+/-0.05 x 10(-3) mm(2)/s) and normal control (FA = 0.32+/-0.04, MD = 1.0+/-0.06 x 10(-3) mm(2)/s) white matter. Significantly increased MD and decreased FA values were also observed in the polymicrogyric cortex (FA = 0.08+/-0.01, MD = 1.2+/-0.10 x 10(-3) mm(2)/s) as compared to normal contralateral (FA = 0.12+/-0.04, MD = 1.1+/-0.09 x 10(-3) mm(2)/s) and normal control (FA = 0.12+/-0.01, MD = 1.1+/-0.09 x 10(-3) mm(2)/s) cortex. CONCLUSION: Significantly decreased FA values with no change in MD values in the subcortical white matter subjacent to polymicrogyric cortex reflect microstructural changes in the white matter probably due to the presence of ectopic neurons.

Adult↗
PubMed2006

Advocacy skills training for young adult cancer survivors: the Young Adult Survivors Conference at Camp Māk-a-Dream.

GOALS OF THE WORK: This manuscript reports on the design, implementation, and evaluation of the Young Adult Survivor Conference (YASC)-a 4-day retreat designed to provide an educational and support experience for cancer survivors diagnosed as children, adolescents, and young adults. The goals of the program were to address issues of survivorship, provide cancer education and tools for self-advocacy, and build bridges of support among young adult cancer survivors who may be experiencing similar journeys through life. THE PROGRAM: YASC was designed to offer advocacy skills specific to participants' needs. Workshops focused on understanding late effects, mentoring and communication, tips for starting peer support programs and networks, and opportunities for offering public testimony and involvement in public policy. EVALUATION: Program evaluation indicated that participants achieved personal goals and expectations for having fun, meeting other survivors, understanding more about their cancer and potential late effects, and learning about how to tell their story so that it will help others. CONCLUSIONS: Involvement with peers who have shared a similar experience provided participants an opportunity to address areas of concern such as coping with uncertainty, dependency vs autonomy, social exclusion, body image, intimacy, sexuality and fertility, and career options. Participation in programs such as the YASC offers young survivors opportunities for life experiences that may promote successful achievement of age-appropriate developmental tasks.

Adaptation, Psychological↗
PubMed2003

Susceptibility of oral bacteria to an antimicrobial decapeptide.

Naturally occurring antimicrobial peptides have emerged as alternative classes of antimicrobials. In general, these antimicrobial peptides exhibit selectivity for prokaryotes and minimize the problems of engendering microbial resistance. As an alternative method to search for more effective broad-spectrum peptide antimicrobials, investigators have developed peptide libraries by using synthetic combinatorial technology. A novel decapeptide, KKVVFKVKFK (KSL), has been identified that shows a broad range of antibacterial activity. The purpose of this study was to test the efficacy of this antimicrobial peptide in killing selected strains of oral pathogens and resident saliva bacteria collected from human subjects. Cytotoxic activity of KSL against mammalian cells and the structural features of this decapeptide were also investigated, the latter by using two-dimensional NMR in aqueous and DMSO solutions. MICs of KSL for the majority of oral bacteria tested in vitro ranged from 3 to 100 microg ml(-1). Minimal bactericidal concentrations of KSL were, in general, within one to two dilutions of the MICs. KSL exhibited an ED(99) (the dose at which 99 % killing was observed after 15 min at 37 degrees C) of 6.25 microg ml(-1) against selected strains of Lactobacillus salivarius, Streptococcus mutans, Streptococcus gordonii and Actinobacillus actinomycetemcomitans. In addition, KSL damaged bacterial cell membranes and caused 1.05 log units reduction of viability counts of saliva bacteria. In vitro toxicity studies showed that KSL, at concentrations up to 1 mg ml(-1), did not induce cell death or compromise the membrane integrity of human gingival fibroblasts. NMR studies suggest that KSL adopts an alpha-helical structure in DMSO solution, which mimics the polar aprotic membrane environment, whereas it remains unstructured in aqueous medium. This study shows that KSL may be a useful antimicrobial agent for inhibiting the growth of oral bacteria that are associated with caries development and early plaque formation.

Aggregatibacter actinomycetemcomitans↗
PubMed2001

[Coarse woody debris and its function in forest ecosystem].

Coarse woody debris (CWD) is an important structural and functional element in forest ecosystem. In this paper, the definition, dynamics, and role of CWD in a forest ecosystem were overviewed. CWD include all woody debris above and under the ground with a diameters > or = 2.5 cm, and mainly comes from the dead trees resulted from competition and disturbances. The biomass of CWD changes like "U" form along with the development of a forest community. The decay rate of CWD is determined by the compound course of the respiration and natural fragmentation. Insects and microorganisms play an important role in the course. CWD basically has two functions in an ecosystem. One is as the nutrition pool for some living creatures, and the other is that the large CWD can form some special habitats for animals and plants. Conclusively these two functions are helpful to reserve the biodiversity and the integrity of ecological process in a natural ecosystem. Gaps are formed while dead trees falling down, and all gaps in a forest succeed one another randomly in the development of a forest ecosystem, which pushes the inner circulation of the forest. Because of the vital roles of CWD in a forest ecosystem, much more attention should be paid in the management of forest ecosystem.

Ecosystem↗
PubMed2001

[Analysis on the trace element and amino acid content in xinjiang 6 series Rhodiola L. plant].

Trace elements Na, K, Mg, Ca, Mn, Fe, Cu, Zn, Se and 20 kinds of amino acid in Xinjiang 6 series of Rhodiola's root and rootstalk were measured. The result shows that contents of 9 kinds of trace elements in them are different. They contain from 8 to 18 kinds amino acid, and also contain from 3 to 7 kinds of indispensable amino acid respectively. Rhodiola rosea L. contains most kinds of amino acid among six kinds of Rhodiola L. in Xingjiang, and contents of trace elements in it are also moderate, so it is fittest to be a nutrious chinese traditional and herbal drug of six kinds of Rhodiola L. in Xingjiang.

Amino Acids↗
PubMed2000

Effects of Kampo medicine, Toki-shakuyaku-san (Tang-Kuei-Shao-Yao-San), on choline acetyltransferase activity and norepinephrine contents in brain regions, and mitogenic activity of splenic lymphocytes in ovariectomized mice.

We investigated the effects of Toki-shakuyaku-san (TSS, Tang-Kuei-Shao-Yao-San in Chinese), Japanese traditional herbal medicine, on the nervous and immune systems in ovariectomized mice as a climacteric disorder model. Female C57BL/6 mice were ovariectomized (OVX) and TSS was given daily through the drinking water for either 10 or 20 days from the day after ovariectomy. After completion of experimental sessions, animals were sacrificed and specific brain regions were assayed for choline acetyltransferase (ChAT) activity and norepinephrine contents. The mitogenic activities, alkaline phosphatase activity and 3-(4, 5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H terazolium bromide (MTT) activity, in splenic lymphocytes has also measured. Furthermore, the effects of TSS on learning and memory ability were studied by the step-through type passive avoidance test. As the results, the administration of TSS significantly suppressed the decrease of ChAT activity in the cerebral cortex (CC) and the dorsal hippocampus (DH) of ovariectomized mice at 10 days after ovariectomy, however no significant effect was observed at 20 days after ovariectomy. Norepinephrine contents in OVX group were decreased at 10 and 20 days after ovariectomy in the CC and the ventral hippocampus (VH). The administration of TSS significantly suppressed the decrease of norepinephrine contents at 20 days after ovariectomy. The mitogenic activities of lymphocyte in spleen were increased at 10 days after ovariectomy, and decreased at 20 days after ovariectomy. However, the suppression of these changes was observed in the group given TSS. The mean latent period was also shortened in the passive avoidance test in the OVX group, but TSS treated group improved mean latency. From these observations, it is inferred that administration of TSS brings on the synthesis of acetylcholine and norepinephrine in the CC and hippocampus, and may improve the memory related behavior and the abnormalities in lymphocytes in the models of the climacteric disorder.

Animals↗
PubMed2000

Impermeability of the GIRK2 weaver channel to divalent cations.

A single amino acid mutation (G156S) in the putative pore-forming region of the G protein-sensitive, inwardly rectifying K(+) channel subunit, GIRK2, renders the conductance constitutively active and nonselective for monovalent cations. The mutant channel subunit (GIRK2wv) causes the pleiotropic weaver disease in mice, which is characterized by the selective vulnerability of cerebellar granule cells and Purkinje cells, as well as dopaminergic neurons in the mesencephalon, to cell death. It has been proposed that divalent cation permeability through constitutively active GIRK2wv channels contributes to a rise in internal calcium in the GIRK2wv-expressing neurons, eventually leading to cell death. We carried out comparative studies of recombinant GIRK2wv channels expressed in Xenopus oocytes and COS-7 cells to determine the magnitude and relative permeability of the GIRK2wv conductance to Ca(2+). Data from these studies demonstrate that the properties of the expressed current differ in the two systems and that when recombinant GIRK2wv is expressed in mammalian cells it is impermeable to Ca(2+).

Animals↗
PubMed1999

The inwardly rectifying K(+) channel subunit GIRK1 rescues the GIRK2 weaver phenotype.

The weaver (wv) gene has been identified as a glycine to serine substitution at residue 156 in the H5 region of inwardly rectifying K(+) channel, GIRK2. The mutation is permissive for the expression of homotetrameric channels that are nonselective for cations and G-protein-independent. Coexpression of GIRK2wv with GIRK1, GIRK2, or GIRK3 in Xenopus oocytes along with expression of subunit combinations linked as dimers and tetramers was used to investigate the effects of the pore mutation on channel selectivity and gating as a function of relative subunit position and number within a heterotetrameric complex. GIRK1 formed functional, K(+) selective channels with GIRK2 and GIRK3. Coexpression of GIRK2wv with GIRK1 gave rise to a component of K(+)-selective, G-protein-dependent current. Currents resulting from coexpression of GIRK2wv with GIRK2 or GIRK3 were weaver-like. Current from dimers of GIRK1-GIRK2wv, GIRK2-GIRK2wv, and GIRK3-GIRK2wv was phenotypically similar to that obtained from coexpression of monomers. Linked tetramers containing GIRK1 and GIRK2wv in an alternating array gave rise to wild-type, K(+)-selective currents. When two mutant subunits were arranged adjacently in a tetramer, currents were weaver-like. These results support the hypothesis that in specific channel stoichiometries, GIRK1 rescues the weaver phenotype and suggests a basis for the selective neuronal vulnerability that is observed in the weaver mouse.

Amino Acid Substitution↗
PubMed1999

[The genotype of vac A gene of Helicobacter pylori (Hp) and its correlation with the gastroduodenal diseases associated with Hp].

OBJECTIVE: To analyze the expression of vac A gene of Helicobacter pylori (Hp) isolated from Chinese patients and to find out the relationship between the genotype of Hp vac A and the gastroduodenal diseases associated with Hp. METHODS: Clones of Hp obtained from patients with gastroduodenal diseases were cultured and mRNA extraction was performed with reverse transcriptase polymerase chain reaction (RT-PCR). RESULTS: 92% of the strains isolated in Shanghai (China) was found to be s1/m2. Strains expressing s1/m1 forms were obtained in 4 cases. s2 form was not found. CONCLUSION: The overwhelming majority of strains isolated from Shanghai patients expresses s1/m2 from. The s1/m2 genotype is dispersed in all of the gastroduodenal diseases associated with Hp.

Adolescent↗
PubMed1999

[Radiofrequency treatment of ethmoidal nerve with allergic rhinitis under nasal endoscopy].

OBJECTIVE: To study the effect of radiofrequency treatment of ethmoidal nerve on allergic rhinitis. METHOD: Eighty-eight cases of allergic rhinitis were treated with ethmoidal nerve radiofrequency under nasal endoscopy. RESULT: It showed marked effectiveness in 73 cases (83.0%), immprovement in 11 cases (12.5%) and failed in 4 cases (4.5%) in one year follow-up. The overall effective rate was 95.5%. CONCLUSION: This result indicated that it is a choice for treating allergic rhinitis to apply ethmoidal nerve radiofrequency under nasal endoscopy.

Adolescent↗
PubMed1998

Isotope dilution-liquid chromatography/electrospray ionization-tandem mass spectrometry for the determination of serum thyroxine as a potential reference method.

A new candidate reference method is presented for the determination of thyroxine in serum. The method is based on isotope dilution-liquid chromatography/tandem mass spectrometry using electrospray for ionization. The internal standard used was 13C6-thyroxine, sample pretreatment consisted of protein precipitation and a two-step liquid/liquid extraction procedure, HPLC was performed on a C-18 column with an eluent containing methanol/water/formic acid (60:40:0.1, by volume), and finally thyroxine and its isotopically labeled analogue were measured in the selected reaction monitoring mode for the transitions m/z 777.7--> 731.7 and m/z 783.7--> 737.7, respectively. The detection limit for thyroxine was 6 pg, the within-run coefficient of variation was 1.1%. The samples were measured in six-fold: in duplicate on three independent days. The mean overall coefficient of variation of the method was 1.6%. The new method was evaluated by measuring nine control sera previously determined by an existing ID-GC/MS method. The differences between the results of the two methods ranged from-1.6% to +3.3%, with a mean of +0.2%.

Calibration↗
PubMed1997

Identification of the membrane-type matrix metalloproteinase MT1-MMP in osteoclasts.

The osteoclasts are the cells responsible for bone resorption. Matrix metalloproteinases (MMPs) appear crucial for this process. To identify possible MMP expression in osteoclasts, we amplified osteoclast cDNA fragments having homology with MMP genes, and used them as a probe to screen a rabbit osteoclast cDNA library. We obtained a cDNA of 1,972 bp encoding a polypeptide of 582 amino acids that showed more than 92% identity to human, mouse, and rat membrane-type 1 MMP (MT1-MMP), a cell surface proteinase believed to trigger cancer cell invasion. By northern blotting, MT1-MMP was found to be highly expressed in purified osteoclasts when compared with alveolar macrophages and bone stromal cells, as well as with various tissues. In situ hybridization on bone sections showed that MT1-MMP is expressed also in osteoclasts in vivo. Antibodies recognizing MT1-MMP reacted with specific plasma membrane areas corresponding to lamellipodia and podosomes involved, respectively, in migratory and attachment activities of the osteoclasts. These observations highlight how cells might bring MT1-MMP into contact with focal points of the extracellular matrix, and are compatible with a role of MT1-MMP in migratory and attachment activities of the osteoclast.

Amino Acid Sequence↗
PubMed1997

Identification and characterization of the insulin-like growth factor I receptor in mature rabbit osteoclasts.

In this study, the insulin-like growth factor I (IGF-I) receptor was identified in rabbit osteoclasts at mRNA and protein levels by in situ hybridization and autoradiography, respectively. Using highly purified mature osteoclasts, the IGF-I receptor was characterized on the molecular level according to its size and its affinity and number per osteoclast by isolation of the receptor-ligand complex and by binding studies, respectively, and on the cellular level according to the response of mature osteoclasts to IGF-I stimulation. In situ hybridization and autoradiography experiments showed that osteoclasts express IGF-I receptor mRNA and IGF-I binding sites. Chemical cross-linking of 125I-IGF-I bound to the purified mature osteoclasts and subsequent sodium dodecyl sulfide-polyacrylamide gel electrophoresis revealed the specific binding of 125I-IGF-I in complexes with molecular masses of 130 and 230-RD consistent with binding to the IGF-I receptor. In competition experiments, 125I-IGF-I binding to mature osteoclasts was dose-dependently reduced by unlabeled IGF-I in the picomolar range, whereas 20 nM insulin did not reduce the binding of 125I-IGF-I binding. The calculated receptor number was 6000 per osteoclast, and the Kd was 0.10 nM. Searching for a role of the IGF-I receptor in mature osteoclasts, we found no significant influence of IGF-I on the levels of the proform of matrix metaloproteinase 9 and tartrate-resistant acid phosphatase. However, the induction of nuclear fragmentation in serum-depleted cultures of purified mature osteoclasts was dose-dependently inhibited by IGF-I in the picomolar range, but not by 1 nM insulin. These data show that functionally active IGF-I receptor is present in mature osteoclasts.

Animals↗
PubMed1997

[Possible significance of novel DNA fragments frequently deleted from tumor cell lines of human esophageal cancer].

OBJECTIVE: To disclose the genetic susceptibility and carcinogenesis mechanism of esophageal cancer (EC) through finding out tumor suppressor genes. METHODS: Twenty EC tissues paired with adjacent normal mucosa and three high-risk EC families were analysed by PCR and Southern blot with DNA probes (12H2, 33B2, and 33B3) frequently deleted from EC cell lines. RESULTS: In surgical samples, the deletion frequency of the fragment 12H2 was highest, i.e. 61% in EC tissues and 22% in adjacent mucosa. The rate of tumor metastasis to lymph nodes was 45%. For the fragment 33B2, they were 30%, 10% and 50%, respectively. But only 20%, 10% and 25% were of the fragment 33B3. No genetic changes were found in the three high-risk EC families for 12H2 and 33B3. The deletion of 33B2 was seen in the proband of one family. CONCLUSION: The fragments 12H2, 33B2 and 33B3 may be candidates of tumor suppressor genes correlative with progression and metastasis of esophageal cancer.

Adult↗
PubMed1997

[Isolation and identification of DNA fragments frequently deleted from tumor cell lines of human esophageal cancer].

OBJECTIVE: To clone tumor suppressor genes associated with human esophageal cancer (EC). METHODS: DNA fragments deleted from cell lines of esophageal cancer EC8712 and EC8733 were isolated by using modified genomic substractive hybridization. Twenty EC tissues paired with adjacent normal mucosa were analysed by Southern blot and PCR with these fragments as probes. RESULTS: Seven DNA fragments deleted from EC cell lines obtained were named as 12H1, 12H2, 33H3, 33H4, 12B1, 33B2 and 33B3. Sequencing revealed their size of 512bp, 428bp, 509bp, 355bp, 680bp (partially sequencing), 519bp and 425bp, respectively. 12H1 and 33H3 showed high homology (98%) to a new repeated sequence in human genome. 33H4 displayed 87% nucleotide identity with human alphoid-like repetitive sequence located on chromosome 17. 12B1 was homologous (90%) to LINE 1 transoposon containing two open reading frames. 12H2, 33B2 and 33B3 were novel sequences. These DNA fragments were deleted in 20%-60% of EC tissues and in 10%-20% of adjacent mucosa. CONCLUSIONS: Loss of 33H4 may be accompanied by deletion of an adjacent gene. 12B1 as transposon may suppress the tumorigenesis by activating suppressor genes or/and by inactivating oncogenes. 12H1/33H3, 12H2, 33B2 and 33B3 may be candidates of tumor suppressor genes associated with the development and the progression of esophageal cancer.

Cloning, Molecular↗