Biomedical subjects

Z S Li

Publications and source records attributed to Z S Li.

At least 19 recordsLinked to original sources

PubMed2006

Preparation of bioactive nanotitania ceramics with biomechanical compatibility.

In this article, bioactive nanotitania ceramics with biomechanical compatibility was prepared by using an additive of hydroxyapatite or MgO as particle growth inhibitor. After sintering at 1000 degrees C, the particle size of nanotitania ceramics prepared by using HA as additive (HT) was much smaller than that prepared by using MgO as additive (MT). In simulated body fluid (SBF), HT could induce apatite formation in 4 days, while no apatite could be found on MT even after it was soaked in SBF for 14 days. After Ros17/28 osteoblasts were cultured on the materials for 1, 4, and 6 days, MTT results showed that the osteoblasts on the HT differentiated faster than that on the MT. Mechanical tests results showed that the bending and compressive strength of HT were 160 and 200 MPa, while those of MT were 70 and 88 MPa, respectively. These results demonstrated that it is suitable to prepare bioactive nanotitania ceramics, with biomechanical compatibility, by using HA as particle growth inhibitor.

Animals↗

PubMed2004

Enteric dopaminergic neurons: definition, developmental lineage, and effects of extrinsic denervation.

The existence of enteric dopaminergic neurons has been suspected; however, the innervation of the gut by sympathetic nerves, in which dopamine (DA) is the norepinephrine precursor, complicates analyses of enteric DA. We now report that transcripts encoding tyrosine hydroxylase (TH) and the DA transporter (DAT) are present in the murine bowel (small intestine > stomach or colon; proximal colon > distal colon). Because sympathetic neurons are extrinsic, transcripts encoding TH and DAT in the bowel are probably derived from intrinsic neurons. TH protein was demonstrated immunocytochemically in neuronal perikarya (submucosal >> myenteric plexus; small intestine > stomach or colon). TH, DA, and DAT immunoreactivities were coincident in subsets of neurons (submucosal > myenteric) in guinea pig and mouse intestines in situ and in cultured guinea pig enteric ganglia. Surgical ablation of sympathetic nerves by extrinsic denervation of loops of the bowel did not affect DAT immunoreactivity but actually increased numbers of TH-immunoreactive neurons, expression of mRNA encoding TH and DAT, and enteric DOPAC (the specific dopamine metabolite). The fetal gut contains transiently catecholaminergic (TC) cells. TC cells are the proliferating crest-derived precursors of mature neurons that are not catecholaminergic and, thus, disappear after embryonic day (E) 14 (mouse) or E15 (rat). TC cells appear early in ontogeny, and their development/survival is dependent on mash-1 gene expression. In contrast, the intrinsic TH-expressing neurons of the murine bowel appear late (perinatally) and are mash-1 independent. We conclude that the enteric nervous system contains intrinsic dopaminergic neurons that arise from a mash-1-independent lineage of noncatecholaminergic precursors.

3,4-Dihydroxyphenylacetic Acid↗

PubMed2001

SiCNN--a new stable isomer with Si(triple bond)C triple bonding.

To predict potentially stable molecules with Si(triple bond)C triple bonding, theoretical calculations at the B3LYP/ 6-311G(d) and CCSD(T)/6-311G(2df) (single-point) levels were employed to study the structures, energetics, and isomerization of various SiCN2 isomers. A schematic potential energy surface (PES) of SiCN2 was established to discuss the kinetic stability of the isomers. A new isomer SiCNN was found to possess a typical Si(triple bond)C triple bond, as confirmed by comparative calculations at the B3LYP, QCISD, QCISD(T), CCSD, and CCSD(T) levels on the bond lengths of SiCNN and other experimentally or theoretically known species of RSiCH (R = H, F, Cl, OH). Moreover, SiCNN resides in a very deep potential, the stabilization barrier is at least 53.2 kcal mol(-1). Thus, SiCNN may be considered as the most kinetically stable isomer with Si(triple bond)C triple bonding known to date, and it may represent a very promising molecule for future experimental characterization. In addition, the stability of the other isomers, such as the four linear species SiNCN, SiNNC, NSiCN and NSiNC, a three-membered NNC ring isomer with exocyclic C-Si bonding, and a four-membered SiCNN ring isomer is discussed and compared with SiCNN.

Journal Article↗

PubMed2001

One-week regimens containing ranitidine bismuth citrate, furazolidone and either amoxicillin or tetracycline effectively eradicate Helicobacter pylori: a multicentre, randomized, double-blind study.

BACKGROUND: The metronidazole resistance of Helicobacter pylori strains has increased rapidly. AIM: To evaluate the efficacy and safety of new 1-week regimens containing ranitidine bismuth citrate, furazolidone and either amoxicillin or tetracycline. METHODS: One hundred and twenty patients with H. pylori-positive inactive duodenal ulcer or non-ulcer dyspepsia diagnosed by endoscopy were recruited randomly to receive one of two regimens for 7 days: ranitidine bismuth citrate, 350 mg b.d., furazolidone, 100 mg b.d., and either amoxicillin, 1000 mg b.d. (n=60), or tetracycline, 500 mg b.d. (n=60). H. pylori infection was identified by rapid urease testing and histology. 13C-Urea breath test was performed to evaluate the cure of H. pylori infection at least 4 weeks after completion of triple therapy. RESULTS: The eradication rates of H. pylori by ranitidine bismuth citrate-furazolidone-amoxicillin and ranitidine bismuth citrate-furazolidone-tetracycline regimens were 82% and 85% (P > 0.05), respectively, by intention-to-treat analysis, and 85% and 91% (P > 0.05), respectively, by per protocol analysis. Adverse effects were mild in both ranitidine bismuth citrate-furazolidone-amoxicillin and ranitidine bismuth citrate-furazolidone-tetracycline groups. CONCLUSIONS: One-week regimens containing ranitidine bismuth citrate, furazolidone and amoxicillin or tetracycline are well tolerated and effective for the eradication of H. pylori.

Adolescent↗

PubMed2000

Enhanced multispecificity of arabidopsis vacuolar multidrug resistance-associated protein-type ATP-binding cassette transporter, AtMRP2.

Recent investigations have established that Arabidopsis thaliana contains a family of genes encoding ATP-binding cassette transporters belonging to the multidrug resistance-associated protein (MRP) family. So named because of the phenotypes conferred by their animal prototypes, many MRPs are MgATP-energized pumps active in the transport of glutathione (GS) conjugates and other bulky amphipathic anions across membranes. Here we show that Arabidopsis MRP2 (AtMRP2) localizes to the vacuolar membrane fraction from seedlings and is not only competent in the transport of GS conjugates but also glucuronate conjugates after heterologous expression in yeast. Based on the stimulatory action of the model GS conjugate 2,4-dinitrophenyl-GS (DNP-GS) on uptake of the model glucuronide 17beta-estradiol 17-(beta-d-glucuronide) (E(2)17betaG) and vice versa, double-label experiments demonstrating that the two substrates are subject to simultaneous transport by AtMRP2 and preloading experiments suggesting that the effects seen result from cis, not trans, interactions, it is inferred that some GS conjugates and some glucuronides reciprocally activate each other's transport via distinct but coupled binding sites. The results of parallel experiments on AtMRP1 and representative yeast and mammalian MRPs indicate that these properties are specific to AtMRP2. The effects exerted by DNP-GS on AtMRP2 are not, however, common to all GS conjugates and not simulated by oxidized glutathione or reduced glutathione. Decyl-GS, metolachlor-GS, and oxidized glutathione, although competitive with DNP-GS, do not promote E(2)17betaG uptake by AtMRP2. Reduced glutathione, although subject to transport by AtMRP2 and able to markedly promote E(2)17betaG uptake, neither competes with DNP-GS for uptake nor is subject to E(2)17betaG-promoted uptake. A multisite model comprising three or four semi-autonomous transport pathways plus distinct but tightly coupled binding sites is invoked for AtMRP2.

ATP Binding Cassette Transporter, Subfamily B↗

PubMed2000

Inputs from intrinsic primary afferent neurons to nitric oxide synthase-immunoreactive neurons in the myenteric plexus of guinea pig ileum.

Nitric oxide synthase (NOS) immunoreactivity occurs in two groups of neurons in the guinea pig small intestine: descending interneurons that are also immunoreactive for choline acetyltransferase (ChAT), and inhibitory motor neurons that lack ChAT immunoreactivity. Interneurons that are involved in local reflexes would be expected to have inputs from intrinsic primary afferent (sensory) neurons, most of which are calbindin-immunoreactive. We examined this possibility using triple staining for NOS, ChAT and calbindin immunoreactivity and investigated the relationships between calbindin-immunoreactive varicosities and the cell bodies of NOS-immunoreactive neurons, using high-resolution confocal microscopy and electron microscopy. By confocal microscopy, we found that the cell bodies of ChAT/NOS interneurons received 84 +/- 23 (mean +/- SD) direct appositions from calbindin-immunoreactive varicosities and that the cell bodies of NOS-inhibitory motor neurons received 82 +/- 20 appositions. Electron-microscopic examination of the relations of 265-calbindin-immunoreactive varicosities, at distances within the resolution of the confocal microscope (300 nm), to 30 NOS-immunoreactive nerve cells indicated that 84% formed close contacts or synapses and 16% were separated from neurons by thin glial cell processes. Thus, each NOS-immunoreactive nerve cell receives about 70 synaptic inputs or close contacts from the calbindin-immunoreactive varicosities of intrinsic primary afferent neurons. It is concluded that there are monosynaptic reflex connections in which intrinsic primary afferent neurons synapse directly with motor neurons and di- or poly-synaptic reflexes in which ChAT- and NOS-immunoreactive neurons are interneurons, interposed between intrinsic primary afferent neurons and NOS-inhibitory neurons.

Afferent Pathways↗

PubMed2000

[Genetical effect of different rye chromosomes on the acid phosphatase (Acph) secretion of common wheat roots under phosphorus starvation conditions].

The effects of different rye chromosomes on Acph secretion of common wheat roots under P starvation conditions were studied by using a set of Chinese Spring-Imperial (CS-IMP) alien addition lines as materials. The Acph activity measurement results showed that P starvation is an induction factor for Acph gene expression; Different chromosomes of Imperial rye in Chinese Spring background has different effects on the secretion of Acph by corresponding addition line roots. Among them, chromosome 1R had the strongest promoting effect; The IEF diagram of Acph isozymes clearly demonstrated that chromosome 1R in rye genome carries P starvation inducible Acph gene(s).

Acid Phosphatase↗

PubMed2000

[The genetic behavior of an Agropyron intermedium chromosome conferring BYDV resistance in wheat background].

Based on the chromosome origin identification of an Agropyron intermedium chromosome with BYDV resistance in Yi4212, a BYDV-resistant substitution line derived from the hybrids between 77-5433 and Zhong5, its ability compensating the lost wheat chromosomes and its transmission rate were investigated. The results indicated that the BYDV-resistant chromosomes originated from Zhong 5 could compensate the wheat chromosomes of homotologous group 2, 5 and 7. The chromosome conferring resistance to BYDV showed the intendance to substitute 2D rather than 2A, 2B wheat chromosomes in disomic substitution lines. In (77-5433/Zhong 5) selfing F2 population, 10 kinds of chromosome constitutions, including 9 expected and 1 unexpected kinds, and much chromosome number variation and little chromosome structure variation were observed. The transmission rate of the BYDV-resistant chromosome and the gametes carrying this chromosome were 56.3% and 33.0% respectively, both are lower than the expected ratio 75.0% and 50.0%. Some reasons were given to explain the related results, and chromosome in situ hybridization was an efficient and accurate way in studying the alien chromosome behavior in wheat background.

Chromosomes↗

PubMed2000

[Fluorescence in situ hybridization applied to the meiotic analysis and spontaneous chromosome translocation in the pollen mother cells of hybrids of Triticum-Haynaldia].

Fluorescence in situ hybridization was applied to the meiotic analysis and chromosome pairing in the pollen mother cells of hybrids of Triticum-Haynaldia. The results indicated that most (90.5%-93.2%) of the PMCs of two Triticum-Haynaldia hybrids contained two univalents involving one Haynaldia chromosome at metaphase I, and only 1 of 320 PMCs with homologous pairing between one wheat chromosome and one Haynaldia chromosome was observed in the hybrid of Guinong 22 x common wheat Chinese Spring, the frequency was 0.3%. The frequencies of the PMCs with mis-dividing chromosome ranged from 32.7% to 37.5% at anaphase I and from 20.5% to 24.4% at anaphase II in the hybrids between Triticum-Haynaldia. The frequency of Haynaldia chromatin translocating into Triticum chromosome was about 0.7% at anaphase I in the hybrid of Guinong 22 x common wheat Chinese Spring and was 0.8%-1.7% at anaphase II in two wheat-Haynaldia hybrids. Otherwise, the chromosome morphology involving Haynaldia chromatin was observed at preleptotene I, and the frequencies of chromatin nucleus at tetrad stage and at microspore stage were investigated. The time of chromosome translocation in meiosis and the transmitting frequencies of Haynaldia chromosome in wheat background were discussed.

Gene Frequency↗

PubMed2000

[Genetic analysis for introgressive genes of petal color from Gossypium bickii to G. hirsutum L].

The character of red petals with a large basal spot was transferred from Gossypium bickii into G. hirsutum L., and the pure lines (HBRL) with the character were obtained by Liang Zhenglan in 1988. Results of genetic analysis for G. hirsutum pure line of red petals (R3bic) and large basal spot (R2bic) were reported in the present study. The large basal spot was dominant to the small basal-spot and spotlessness of G. hirsutum. R2bic was shown to be allelic to R2 of G. hirsutum, and R2bic, R2 and r2 were multiple alleles. R2bic was found to be linked with Lc1, and linkage between R2bic and Lc1 was estimated at 37.31 +/- 2.44 centimorgans, The red petal (R3bic) was epistatic dominance to the yellow petal (Y1) and cream petal (y1), and R3bic is closely linked with R2bic. It is proposed that the introgressive gene of the large basal spot from G. bickii into G. hirsutum be assigned gene symbol R2bic, and the red petals be given the gene symbol R3bic.

Color↗

PubMed2000

[Measurement for relative molecular mass distribution of lignin dispersants].

Gel chromatography was employed to measure relative molecular mass distribution of lignin dispersants. The results show that relative molecular mass distribution of Reax-85A(I) and M-9(II) are respectively to be from 500 to 35,000 and from 1,000 to 50,000. The fractions separated from (I) and (II) by thin layer chromatography were also investigated through gel chromatography to prove that these fractions were mainly separated depending on relative molecular mass.

Chromatography, Gel↗

PubMed1998

Immunohistochemical localisation of cholinergic markers in putative intrinsic primary afferent neurons of the guinea-pig small intestine.

Antibodies against choline acetyltransferase (ChAT) and the vesicular acetylcholine transporter (VAChT) were used to determine whether neurons that have previously been identified as intrinsic primary afferent neurons in the guinea-pig small intestine have a cholinergic phenotype. Cell bodies of primary afferent neurons in the myenteric plexus were identified by their calbindin immunoreactivity and those in the submucous plexus by immunoreactivity for substance P. High proportions of both were immunoreactive for ChAT, viz. 98% of myenteric calbindin neurons and 99% of submucosal substance P neurons. ChAT immunoreactivity also occurred in all nerve cell bodies immunoreactive for calretinin and substance P in the myenteric plexus, but in only 16% of nerve cells immunoreactive for nitric oxide synthase. VAChT immunoreactivity was in the majority of calbindin-immunoreactive varicosities in the myenteric ganglia, submucous ganglia and mucosa and also in the majority of the varicosities of neurons that were immunoreactive for calretinin and somatostatin and that had been previously established as being cholinergic. We conclude that the intrinsic primary afferent neurons are cholinergic and that they may release transmitter from their sensory endings in the mucosa.

Afferent Pathways↗

PubMed1998

Morphological and immunohistochemical identification of neurons and their targets in the guinea-pig duodenum.

Nerve circuits within the proximal duodenum were investigated using a combination of immunohistochemistry for individual neuron markers and lesion of intrinsic nerve pathways to determine axon projections. Cell shapes and axonal projections were also studied in cells that had been injected with a marker substance. Several major neuron populations were identified. Calbindin immunoreactivity occurred in a population of myenteric nerve cells with Dogiel type II morphology. These had axons that projected to other myenteric ganglia, to the circular muscle and to the mucosa. All were immunoreactive for the synthesizing enzyme for acetylcholine, choline acetyltransferase, and some were also immunoreactive for calretinin. Myenteric neurons with nitric oxide synthase immunoreactivity projected anally to the circular muscle. These were also immunoreactive for vasoactive intestinal peptide, and proportions of them had enkephalin and/or neuropeptide Y immunoreactivity. It is suggested that they are inhibitory motor neurons to the circular muscle. A very few (about 2%) of nitric oxide synthase-immunoreactive neurons had choline acetyltransferase immunoreactivity. Tachykinin (substance P)-immunoreactive nerve cells were numerous in the myenteric plexus. Some of these projected orally to the circular muscle and are concluded to be excitatory motor neurons. Others projected to the tertiary plexus which innervates the longitudinal muscle and others provided terminals in the myenteric plexus. Two groups of descending interneurons were identified, one with somatostatin immunoreactivity and one with vasoactive intestinal peptide immunoreactivity. The two most common nerve cells in submucous ganglia were neuropeptide Y- and vasoactive intestinal peptide-immunoreactive nerve cells. Both provided innervation of the mucosa. There was also a population of calretinin-immunoreactive submucous neurons that innervated the mucosal glands, but not the villi. Comparison with the ileum reveals similarities in the chemistries and projections of neurons. Differences include the almost complete absence of nitric oxide synthase immunoreactivity from vasoactive intestinal peptide-immunoreactive interneurons in the duodenum, the projection of calbindin-immunoreactive Dogiel type II neurons to the circular muscle and the absence of tachykinin-immunoreactivity from these neurons.

Animals↗

PubMed1998

Innervation of intestinal arteries by axons with immunoreactivity for the vesicular acetylcholine transporter (VAChT).

The presence of a cholinergic innervation of arterioles within the gut wall is suggested by pharmacological studies of nerve mediated vasodilatation, but attempts to identify nerve cells that give rise to cholinergic vasodilator fibres have yielded discrepant results. In the present work, antibodies to the vesicular acetylcholine transporter protein (VAChT) were used to investigate the relationships of immunoreactive nerve fibres to submucosal arterioles. Comparison was made with cerebral arteries, which are known to be cholinergically innervated. Double labelling immunohistochemical techniques revealed separate VAChT and tyrosine hydroxylase (TH) immunoreactive (IR) fibres innervating all sizes of arteries of the submucosa of the stomach, ileum, proximal colon, distal colon and rectum as well as the cerebral arteries. Arterioles of all digestive tract regions had greater densities of TH-IR innervation than VAChT-IR innervation. In the ileum, double labelling for VAChT-IR and VIP-IR or calretinin-IR showed more VAChT-IR than either VIP-IR or calretinin-IR fibres. Calretinin-IR and VAChT-IR were colocalised in a majority of calretinin-IR axons, but VIP-IR and VAChT-IR were not colocalised. All calretinin-IR nerve cells in submucous ganglia were immunoreactive for choline acetyltransferase, but only 1-2% of VIP-IR nerve cells were immunoreactive. Extrinsic denervation of the ileum did not alter the distribution of VAChT-IR fibres, but it eliminated TH-IR fibres. Removal of myenteric ganglia (myectomy) did not alter the distribution of fibres with VAChT or TH-IR. This work thus provides evidence for cholinergic innervation of intrinsic arterioles throughout the digestive tract and indicates that the fibres in the small intestine originate from submucosal nerve cells.

Animals↗

PubMed1998

AtMRP2, an Arabidopsis ATP binding cassette transporter able to transport glutathione S-conjugates and chlorophyll catabolites: functional comparisons with Atmrp1.

Three ATP binding cassette (ABC) transporter-like activities directed toward large amphipathic organic anions have recently been identified on the vacuolar membrane of plant cells. These are the Mg-ATP-energized, vanadate-inhibitable vacuolar accumulation of glutathione S-conjugates (GS conjugates), chlorophyll catabolites, and bile acids, respectively. Although each of these activities previously had been assigned to distinct pumps in native plant membranes, we describe here the molecular cloning, physical mapping, and heterologous expression of a gene, AtMRP2, from Arabidopsis thaliana that encodes a multispecific ABC transporter competent in the transport of both GS conjugates and chlorophyll catabolites. Unlike its isoform, AtMRP1, which transports the model Brassica napus chlorophyll catabolite transporter substrate Bn-NCC-1 at low efficiency, heterologously expressed AtMRP2 has the facility for simultaneous high-efficiency parallel transport of GS conjugates and Bn-NCC-1. The properties of AtMRP2 therefore establish a basis for the manipulation of two previously identified plant ABC transporter activities and provide an explanation for how the comparable transporter in native plant membranes would be systematically mistaken for two distinct transporters. These findings are discussed with respect to the functional organization of AtMRP2, the inability of AtMRP2 and AtMRP1 to transport the model bile acid transporter substrate taurocholate (despite the pronounced sensitivity of both to direct inhibition by this agent), the differential patterns of expression of their genes in the intact plant, and the high capacity of AtMRP2 for the transport of glutathionated herbicides and anthocyanins.

ATP-Binding Cassette Transporters↗

PubMed1998

Role of dNTPs in mutagenesis.

The induced mutation frequency by alkylating mutagen glycidyl methacrylate (GMA) and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) was investigated with or without perturbation of deoxyribonucleoside triphosphate (dNTP) pools; the influence of short treatment at different concentrations of GMA or MNNG on dNTP pools was also explored. The results indicated that the induced mutation frequency increased greatly at high dosages of mutagen (GMA approximately 64 micrograms/ml, MNNG approximately 8 micrograms/ml) and the perturbation on dNTP pools was carried out before the treatment of mutagen; the short treatment with mutagen could induce distinct fluctuations of dNTP pools, but different mutagen might have different effects on dNTP pools. According to the results of the present study and other reports in literature, we conclude that dNTP pools may be the targets of alkylating mutagens and the fluctuations of dNTP pools are closely associated with mutagenesis.

3T3 Cells↗

PubMed1998

Role of deoxyribonucleoside triphosphates (dNTPs) in cell transformation.

Deoxyribonucleoside triphosphate (dNTP) pools were measured in normal BALB/c3T3 cells, transformation-treated cells and transformed cells with reverse-phase HPLC. The fluctuation of dNTP pools was similar after transformation treatment with alkylating mutagen glycidyl methacrylate (GMA) or Nmethyl-N'-nitro-N-nitrosoguanidine (MNNG). However, the gap between deoxyguanosine triphosphate + deoxyadenosine triphosphate (dGTP + dATP) pools and deoxythymidine triphosphate + deoxycytidine triphosphate (dTTP + dCTP) pools was greatly intensified. The measurements also indicated that the dNTP pools in transformed cells were quite different from those in normal cells. The results suggested that dNTP pools may play an important role in cell transformation.

3T3 Cells↗

PubMed1998

The diagnostic value of transendoscopic miniature ultrasonic probe for esophageal diseases.

BACKGROUND AND STUDY AIMS: To investigate the value of a transendoscopic miniature ultrasonic probe (USP) in the diagnosis of esophageal diseases. PATIENTS AND METHODS: Endoscopic ultrasonography was performed by means of USP in 53 patients with esophageal diseases, including 16 with esophageal leiomyoma, 14 with esophageal carcinoma, seven with achalasia, seven with reflux esophagitis, six with esophageal polyps and three with esophageal varices. RESULTS: USP clearly showed all 16 esophageal leiomyomas, whereas, conventional EUS could not show five small leiomyomas less than 1.0 x 1.0 cm in size. The appearance of esophageal leiomyoma was that of a hypoechoic mass with a homogeneous inner echogram arising from the fourth hypoechoic layer. All 14 patients with esophageal carcinoma underwent full endosonographic T and N staging with USP. In two cases passage of the malignant stenosis proved to be impossible using conventional EUS. The accuracy of USP on T staging and N staging was 80% and 30%, respectively. In the seven achalasia patients USP demonstrated a seven-layer structure of the esophageal wall, with thickening of the third and fifth layers. In the seven patients with reflux esophagitis no difference was found for the ultrasonic image between that with and that without Barrett's epithelium. All of the esophageal polyps were showed by USP as hypoechoic homogeneous lesion with indistinct margins. After endoscopic sclerotherapy the ultrasonographic feature of esophageal varices changed from submucosal multiple anechoic areas to high echoic areas. CONCLUSION: With refinement, the transendoscopic miniature ultrasonic probe will play an increasing role in the diagnosis of esophageal disease.

Endosonography↗