Biomedical subjects

H Lin

Publications and source records attributed to H Lin.

At least 109 records · Page 6Linked to original sources

PubMed2000

Direct effects of propylthiouracil on testosterone secretion in rat testicular interstitial cells.

The aim of this study was to investigate the mechanism by which propylthiouracil (PTU) exerts its inhibitory effects on the production of testosterone by rat testicular interstitial cells. The plasma testosterone concentration was decreased 60 and 120 min after an intravenous infusion of PTU (10 or 20 mg kg(-1)), but the concentration of plasma T(4) was unaffected by the drug treatment. Exposure of anterior pituitary tissue to PTU (3-12 mM) in vitro did not affect either basal or gonadotropin-releasing hormone (GnRH)-stimulated luteinizing hormone (LH) release. PTU (3 - 12 mM) inhibited both the basal and the human chorionic gonadotropin (hCG, 0.05 i.u. ml(-1))-stimulated release of testosterone from rat testicular tissue in vitro; at the highest concentration tested (12 mM), it also inhibited the forskolin or 8-bromo-adenosine 3':5'-cyclic monophosphate (8-Br-cyclic AMP)-stimulated release of testosterone. The 25-OH-cholesterol (10(-7)-10(-5) M)-stimulated release of pregnenolone and testosterone by the testicular interstitial cells was inhibited by PTU (12 mM, P<0.05). The results suggest that the inhibitory actions of PTU on testosterone secretion are exerted, at least in part, at the testicular level through a mechanism which is independent of thyroid status and which involves a reduction in P450scc activity and, hence, in the conversion of cholesterol to pregnenolone.

Animals↗

PubMed2000

Measuring diet quality in china: the INFH-UNC-CH diet quality index.

OBJECTIVE: This paper describes the development and efficacy of a diet quality index (DQI) for China. DESIGN: The Dietary Guidelines for Chinese Residents motivated the selection of 10 DQI components. These components were weighted and assigned cut-offs and point schemes based on the Chinese Food Guide Pagoda, Chinese and/or international dietary reference values. The efficacy of resulting DQI scores was assessed relative to a priori expectations. SUBJECTS: The Chinese DQI was evaluated using cross-sectional 3 day diet record and anthropometric data on 7450 adults from the 1991 China Health and Nutrition Survey. METHODS: For each individual, a DQI total score was calculated as the sum of components, and DQI pattern scores calculated to reflect the underlying composition of diet quality problems. The DQI scores were compared with component scores, food and nutrient intake, weight status and sociodemographic variables. RESULTS: The total DQI score simultaneously represented all component aspects of diet quality as well as micronutrients not explicitly built into the index. The total DQI score was significantly correlated with food and nutrient intakes, BMI, urban residence and income. The DQI pattern scores correlated with DQI components and weight status as expected. CONCLUSIONS: The China DQI captures variation along several components of diet quality, appears sensitive to under- and overnutrition, as well as sociodemographic variables. The China DQI may prove useful for monitoring the nutrition transition and epidemiologic trends in China. SPONSORSHIP: National Institutes of Health (HD 38700 and R01-HD30880) and the Chinese Academy of Preventive Medicine.

Adult↗

PubMed2000

Outcome of preterm infants with congenital heart disease.

OBJECTIVES AND STUDY DESIGN: To evaluate the morbidity and mortality of preterm infants with congenital heart disease (CHD), a chart review was performed for infants with CHD, excluding isolated patent ductus arteriosus, who were <37 weeks' gestation, weighed <2500 g, and were admitted to our neonatal intensive care unit from 1976 to 1999 (N = 201). RESULTS: Patients in the study represented 1.9% of the total neonatal intensive care unit population <37 weeks' gestation and <2500 g. The median gestational age was 33 weeks, and the mean birth weight was 1852 g. CHD diagnosis frequencies were similar to those reported in other large incidence studies, except for a higher percentage of conotruncal defects. The risk of necrotizing enterocolitis was 1.7 times higher and the overall mortality twice as high in our patients compared with patients in the neonatal intensive care unit who did not have CHD. Cardiac surgery (n = 133) was performed on 108 patients. During the recent period of 1985 to 1999, compared with our institution's overall results for CHD surgery, the operative mortality rate was 10.4% versus 5.4% for closed procedures and 25.4% versus 10.5% for open procedures. The actuarial survival rate is 51% at 10 years; survival improved as the study period progressed. CONCLUSIONS: Infants with both CHD and prematurity did significantly worse than either group alone. Such outcome data are required for proper allocation of resources to care for this high-risk pediatric population.

Cardiac Surgical Procedures↗

PubMed2000

Identification of heading date quantitative trait locus Hd6 and characterization of its epistatic interactions with Hd2 in rice using advanced backcross progeny.

A backcrossed population (BC(4)F(2)) derived from a cross between a japonica rice variety, Nipponbare, as the recurrent parent and an indica rice variety, Kasalath, as the donor parent showed a long-range variation in days to heading. Quantitative trait loci (QTL) analysis revealed that two QTL, one on chromosome 3, designated Hd6, and another on chromosome 2, designated Hd7, were involved in this variation; and Hd6 was precisely mapped as a single Mendelian factor by using progeny testing (BC(4)F(3)). The nearly isogenic line with QTL (QTL-NIL) that carries the chromosomal segment from Kasalath for the Hd6 region in Nipponbare's genetic background was developed by marker-assisted selection. In a day-length treatment test, the QTL-NIL for Hd6 prominently increased days to heading under a 13.5-hr day length compared with the recurrent parent, Nipponbare, suggesting that Hd6 controls photoperiod sensitivity. QTL analysis of the F(2) population derived from a cross between the QTL-NILs revealed existence of an epistatic interaction between Hd2, which is one of the photoperiod sensitivity genes detected in a previous analysis, and Hd6. The day-length treatment tests of these QTL-NILs, including the line introgressing both Hd2 and Hd6, also indicated an epistatic interaction for photoperiod sensitivity between them.

Chromosome Mapping↗

PubMed2000

Fresh and globular amyloid beta protein (1-42) induces rapid cellular degeneration: evidence for AbetaP channel-mediated cellular toxicity.

Amyloid beta peptides (AbetaP) deposit as plaques in vascular and parenchymal areas of Alzheimer's disease (AD) tissues and Down's syndrome patients. Although neuronal toxicity is a feature of late stages of AD, vascular pathology appears to be a feature of all stages of AD. Globular and nonfibrillar AbetaPs are continuously released during normal cellular metabolism, form calcium-permeable channels, and alter cellular calcium level. We used atomic force microscopy, laser confocal microscopy, and calcium imaging to examine the real-time and acute effects of fresh and globular AbetaP(1-42), AbetaP(1-40), and AbetaP(25-35) on cultured endothelial cells. AbetaPs induced morphological changes that were observed within minutes after AbetaP treatment and led to eventual cellular degeneration. Cellular morphological changes were most sensitive to AbetaP(1-42). AbetaP(1-42)-induced morphological changes were observed at nanomolar concentrations and were accompanied by an elevated cellular calcium level. Morphological changes were prevented by anti-AbetaP antibody, AbetaP-channel antagonist zinc, and the removal of extracellular calcium, but not by tachykinin neuropeptide, voltage-sensitive calcium channel blocker cadmium, or antioxidants DTT and Trolox. Thus, nanomolar fresh and globular AbetaP(1-42) induces rapid cellular degeneration by elevating intracellular calcium, most likely via calcium-permeable AbetaP channels and not by its interaction with membrane receptors or by activating oxidative pathways. Such rapid degeneration also suggests that the plaques, and especially fibrillar AbetaPs, may not have a direct causative role in AD pathogenic cascades.

Alzheimer Disease↗

PubMed2000

Fresh and nonfibrillar amyloid beta protein(1-40) induces rapid cellular degeneration in aged human fibroblasts: evidence for AbetaP-channel-mediated cellular toxicity.

Alzheimer's disease (AD) is primarily nonfamilial or sporadic (SAD) in origin, although several genetic linkages are reported. Tissues from AD patients contain fibrillar plaques made of 39 to 43 amino acid-long amyloid beta peptide (AbetaP), although the mechanisms of AbetaP toxicity are poorly understood. AbetaP(1-40) is the most prevalent AbetaP present in the neuronal and non-neuronal tissues from SAD patients. AbetaP(1-40) toxicity has been examined mainly after prolonged incubation and correlates with the age and fibrillar morphology of AbetaP(1-40). Globular and nonfibrillar AbetaPs are released continually during normal cellular metabolism; they elevate cellular Ca(2+) and form cation-permeable channels. However, their role in cellular toxicity is poorly understood. We have used an integrated atomic force and light fluorescence microscopy (AFM-LFM), laser confocal microscopy, and calcium imaging to examine real-time and acute effect of fresh and globular AbetaP(1-40) on cultured, aged human, AD-free fibroblasts. AFM images show that freshly prepared AbetaP(1-40) in phosphate-buffered saline (PBS) are globular and do not form fiber for an extended time period. AbetaP(1-40) induced rapid structural modifications, including cytoskeletal reorganization, retraction of cellular processes, and loss of cell-cell contacts, within minutes of incubation. This led to eventual cellular degeneration. AbetaP(1-40)-induced degeneration was prevented by anti-AbetaP antibody, zinc, and Tris, but not by tachykinin neuropeptides. In Ca(2+)-free extracellular medium, AbetaP(1-40) did not induce cellular degeneration. In the presence of extracellular Ca(2+), AbetaP(1-40) induced a sustained increase in the cellular Ca(2+). Thus, short-term and acute AbetaP(1-40) toxicity is mediated by Ca(2+) uptake, most likely via calcium-permeable AbetaP pores. Such rapid degeneration does not require fibrillar plaques, suggesting that the plaques may not have any causative role.

Alzheimer Disease↗

PubMed2000

Neuropilin-1 expression by tumor cells promotes tumor angiogenesis and progression.

Neuropilin-1 (NRP1) is a VEGF(165) and semaphorin receptor expressed by vascular endothelial cells (EC) and tumor cells. The function of NRP1 in tumor cells is unknown. NRP1 was overexpressed in Dunning rat prostate carcinoma AT2.1 cells using a tetracycline-inducible promoter. Concomitant with increased NRP1 expression in response to a tetracycline homologue, doxycycline (Dox), basal cell motility, and VEGF(165) binding were increased three- to fourfold in vitro. However, induction of NRP1 did not affect tumor cell proliferation. When rats injected with AT2.1/NRP1 tumor cells were fed Dox, NRP1 synthesis was induced in vivo and AT2.1 cell tumor size was increased 2.5- to 7-fold in a 3-4 wk period compared to controls. The larger tumors with induced NRP1 expression were characterized by markedly increased microvessel density, increased proliferating EC, dilated blood vessels, and notably less tumor cell apoptosis compared to noninduced controls. It was concluded that NRP1 expression results in enlarged tumors associated with substantially enhanced tumor angiogenesis.

Animals↗

PubMed2000

Cell-penetrating SH3 domain blocker peptides inhibit proliferation of primary blast cells from CML patients.

Bcr-Abl contributes prominently to the development of most chronic myeloid leukemias (CMLs). Prior work has identified the adapter protein CRKL as a major substrate of the Bcr-Abl tyrosine kinase. CRKL can also bind via its first SH3 domain [SH3(1)] to specific sequences in Bcr-Abl. Cell-penetrating peptides were developed that bind with high affinity and selectivity to the SH3(1) domain of CRKL. They disrupt Bcr-Abl-CRKL complexes and strongly reduce the proliferation of primary CML blast cells and cell lines established from Bcr-Abl-positive patients. Activation-specific antibodies against phosphorylated MAP kinase (MAPK) showed that MAPK activity is down-regulated in blast cells treated with the CRKLSH3(1) blocker peptides. We conclude that the Bcr-Abl-CRKL complexes are largely dependent on the CRKLSH3(1) domain, that the central mitogenic cascade is down-regulated as a consequence of the disruption of CRKLSH3(1) interactions, and that CRKL therefore contributes to the proliferation of CML blast cells.

Adaptor Proteins, Signal Transducing↗

PubMed2000

Structure stability of ultraintense laser pulse in transverse homogeneous cold plasma

We study transverse structure symmetry of an ultraintense laser pulse through transverse homogeneous cold plasma. We derive a steady-structure equation of laser pulse and solve it under different on-axis conditions. We compare Hamiltonian values at solutions with different on-axis conditions to examine their relative stability. Numerical results show that for different ionic density, symmetric structure is not always stable relative to asymmetric one of same power. For a given ionic density, whether a symmetric structure is stable is determined by its power. This result agrees with the phenomenon of pulse "head bending", qualitatively. Our theory reveals that, in addition to the plasma's transverse inhomogeneity, there is another mechanism responsible for asymmetric structure.

Journal Article↗

PubMed2000

Dietary Bifidobacterium lactis (HN019) enhances resistance to oral Salmonella typhimurium infection in mice.

The ability of a newly identified probiotic lactic acid bacterial strain, Bifidobacterium lactis (HN019), to confer protection against Salmonella typhimurium was investigated in BALB/c mice. Feeding mice with B. lactis conferred a significant degree of protection against single or multiple oral challenge with virulent S. typhimurium, in comparison to control mice that did not receive B. lactis. Protection included a ten-fold increase in survival rate, significantly higher post-challenge food intake and weight gain, and reduced pathogen translocation to visceral tissues (spleen and liver). Furthermore, the degree of pathogen translocation showed a significant inverse correlation with splenic lymphocyte proliferative responses to mitogens, blood and peritoneal cell phagocytic activity and intestinal mucosal anti-S. typhimurium antibody titers in infected mice; all of these immune parameters were enhanced in mice fed B. lactis. Together, these results suggest that dietary B. lactis can provide a significant degree of protection against Salmonella infection by enhancing various parameters of immune function that are relevant to the immunological control of salmonellosis. Thus dietary supplementation with B. lactis provides a unique opportunity for developing immune-enhancing probiotic dairy food products with proven health benefits.

Animals↗

PubMed2000

Phospholipase C is involved in kinetochore function in Saccharomyces cerevisiae.

The budding yeast PLC1 gene encodes a homolog of the delta isoform of mammalian phosphoinositide-specific phospholipase C. Here, we present evidence that Plc1p associates with the kinetochore complex CBF3. This association is mediated through interactions with two established kinetochore proteins, Ndc10p and Cep3p. We show by chromatin immunoprecipitation experiments that Plc1p resides at centromeric loci in vivo. Deletion of PLC1, as well as plc1 mutations which abrogate the interaction of Plc1p with the CBF3 complex, results in a higher frequency of minichromosome loss, nocodazole sensitivity, and mitotic delay. Overexpression of Ndc10p suppresses the nocodazole sensitivity of plc1 mutants, implying that the association of Plc1p with CBF3 is important for optimal kinetochore function. Chromatin extracts from plc1Delta cells exhibit reduced microtubule binding to minichromosomes. These results suggest that Plc1p associates with kinetochores and regulates some aspect of kinetochore function and demonstrate an intranuclear function of phospholipase C in eukaryotic cells.

Centromere↗

PubMed2000

Divergent N-terminal sequences target an inducible testis deubiquitinating enzyme to distinct subcellular structures.

Ubiquitin-specific processing proteases (UBPs) presently form the largest enzyme family in the ubiquitin system, characterized by a core region containing conserved motifs surrounded by divergent sequences, most commonly at the N-terminal end. The functions of these divergent sequences remain unclear. We identified two isoforms of a novel testis-specific UBP, UBP-t1 and UBP-t2, which contain identical core regions but distinct N termini, thereby permitting dissection of the functions of these two regions. Both isoforms were germ cell specific and developmentally regulated. Immunocytochemistry revealed that UBP-t1 was induced in step 16 to 19 spermatids while UBP-t2 was expressed in step 18 to 19 spermatids. Immunoelectron microscopy showed that UBP-t1 was found in the nucleus while UBP-t2 was extranuclear and was found in residual bodies. For the first time, we show that the differential subcellular localization was due to the distinct N-terminal sequences. When transfected into COS-7 cells, the core region was expressed throughout the cell but the UBP-t1 and UBP-t2 isoforms were concentrated in the nucleus and the perinuclear region, respectively. Fusions of each N-terminal end with green fluorescent protein yielded the same subcellular localization as the native proteins, indicating that the N-terminal ends were sufficient for determining differential localization. Interestingly, UBP-t2 colocalized with anti-gamma-tubulin immunoreactivity, indicating that like several other components of the ubiquitin system, a deubiquitinating enzyme is associated with the centrosome. Regulated expression and alternative N termini can confer specificity of UBP function by restricting its temporal and spatial loci of action.

Age Factors↗

PubMed2000

Lack of angiotensin II-facilitated erythropoiesis causes anemia in angiotensin-converting enzyme-deficient mice.

While nephrologists often observe reduced hematocrit associated with inhibitors of angiotensin-converting enzyme (ACE), the basis for this effect is not well understood. We now report that two strains of ACE knockout mice have a normocytic anemia associated with elevated plasma erythropoietin levels. (51)Cr labeling of red cells showed that the knockout mice have a normal total blood volume but a reduced red cell mass. ACE knockout mice, which lack tissue ACE, are anemic despite having normal renal function. These mice have increased plasma levels of the peptide acetyl-SDKP, a possible stem cell suppressor. However, they also show low plasma levels of angiotensin II. Infusion of angiotensin II for 2 weeks increased hematocrit to near normal levels. These data suggest that angiotensin II facilitates erythropoiesis, a conclusion with implications for the management of chronically ill patients on inhibitors of the renin-angiotensin system.

Anemia↗

PubMed2000

piwi encodes a nucleoplasmic factor whose activity modulates the number and division rate of germline stem cells.

piwi represents the first class of genes known to be required for stem cell self-renewal in diverse organisms. In the Drosophila ovary, piwi is required in somatic signaling cells to maintain germline stem cells. Here we show that piwi encodes a novel nucleoplasmic protein present in both somatic and germline cells, with the highly conserved C-terminal region essential for its function. Removing PIWI protein from single germline stem cells significantly decreases the rate of their division. This suggests that PIWI has a second role as a cell-autonomous promoter of germline stem cell division. Consistent with its dual function, over-expression of piwi in somatic cells causes an increase both in the number of germline stem cells and the rate of their division. Thus, PIWI is a key regulator of stem cell division - its somatic expression modulates the number of germline stem cells and the rate of their division, while its germline expression also contributes to promoting stem cell division in a cell-autonomous manner.

Animals↗

PubMed2000

[Study of covalently immobilizing heparin to polyetherurethane surface].

In this paper an approach of covalently immobilizing heparin to the surface of polyetherurethane without functional groups was studied. By quantitation of amino groups on PEU surface, the appropriate hydrolysis condition to PEU was determined. The assays of the heparin content heparinized PEU and the time of recalcification proved the above approach comparatively ideal.

Heparin↗

PubMed2000

Effects of induction anesthetic agents on outcome of assisted reproductive technology: a comparison of propofol and thiopental sodium.

BACKGROUND: The use of propofol, as compared to barbiturates (e.g. thiopental), for short surgical procedures has been associated with more rapid recovery from the procedure. Propofol, an intravenous anesthetic drug, is frequently used as an adjunct to transvaginal oocyte retrieval but little is known about its effects upon fertilization, embryo development, and pregnancy rate when used drug the for induction of general anesthesia. This study was conducted to compare the outcome of assisted reproductive technology (ART) with the use of propofol versus thiopental sodium for the induction of general anesthesia during oocyte retrieval. METHODS: In this retrospective study, 92 cases of infertile patients who underwent oocyte retrieval under the induction of general anesthesia with, respectively, either propofol (Group I, 72 cases) or thiopental sodium (Group II, 20 cases) were compared for fertilization rate, cleavage rate, and pregnancy rate. RESULTS: The fertilization rate was 68.9% for Group I and 66.7% for group II (p = 0.614). The cleavage rate was 96.5% for Group I and 94.8% for Group II (p = 0.294). The rate of good embryo grading and poor embryo grading was, respectively, 85.1% and 14.9% for Group I, versus 85.7% and 14.3% for Group II (p = 0.887). The pregnancy rate was 30.5% for Group I and 20.0% for Group II (p = 0.354). The implantation rate and abortion rate was, respectively, 9.1% and 18.2% for Group I versus 7.2% and 25.0% for Group II (implantation rate, p = 0.590; abortion rate, p = 0.600). CONCLUSION: There were no significant differences between these two groups for fertilization rate, cleavage rate, pregnancy rate, implantation rate and abortion rate. We suggest cautious use of propofol for the procedure of oocyte retrieval despite its associated more rapid post-operative recovery including less nausea/vomiting.

Anesthetics, Intravenous↗

PubMed2000

[Apoptosis and uterine cervical carcinogenesis].

OBJECTIVE: To investigate the possible role of apoptosis in the development of uterine cervical carcinoma. METHODS: Formalin-fixed, paraffin-embedded samples from 190 patients [41 patients with severe dysplasia (SD); 37 with carcinoma in situ(CIS); 31 with microinvasive carcinoma (MIC), 40 with fran invasive large cell non-keratinizing epidermoid carcinoma (IC)], and 41 samples from normal cervical squamous epithelium (NE) were studied. The number of apoptotic cells was assessed in situ by the TDT-mediated dUTP-biotin nick end labeling (TUNEL) method. PCNA, p53 and bcl-2 were demonstrated immunohistochemically. RESULTS: (1) In NE, TUNEL-positive cells were found in the superficial layer and PCNA-positive cells were confined in the lamina profunda, while in cervical neoplasia these cells were irregulasly scattered throughout the cervical lesions. (2) The TUNEL staining index decreased while PCNA increased with progression of the neoplasm, showing a significant negative correlation between apoptosis and proliferation. (3) In patients with SD and CIS who had overexpression of p53 and bcl-2 proteins, the cells positively stained by TUNEL were significantly less in number than in these with negative p53 and bcl-2 expression. No such observation for PCNA expression. CONCLUSION: These results suggest that apoptosis is associated with the early process of cervical carcinogenesis and apoptosis is closely correlated with overexpression of p53 and bcl-2 proteins.

Apoptosis↗

PubMed2000

[Wetland ecosystems formation and its protection in Yellow River Delta].

Site investigation, satellite photo analysis and historic material analysis show that the vast neonatal wetlands in Yellow River Delta were created by high concentration sediment of the river and the land-sea evolution. Affected by the regional climate, landform, geological deposition, soil, vegetation and their interactions, the wetlands covered 4.5 x 10(5) hm2, 6.84 x 10(4) hm2 of which were artificial wetlands. The wetland ecosystems changed with the waving of the Yellow River Mouth and the land development in the Delta area. From ocean to land, the sublittoral aquatic wetland, eulittoral wetland, eplittoral salt wetland, bulrush-quitch wetland, meadow wetland and land agroecosystem were developed. The wetland ecosystems had abundant biological resources, including 1524 wild animals, 300 birds and 1040 fishes, which were changed recently by the oil development and affected by the interruption of Yellow River. Wetland protection should be strengthened in resources utilization.

Conservation of Natural Resources↗