Search PubMed⌕ Search

Biomedical subjects

Liang Zhao

Publications and source records attributed to Liang Zhao.

At least 55 records · Page 3Linked to original sources
PubMed2004

Self-assembled polynuclear clusters derived from some flexible polydentate dihydrazide ligands.

Polynuclear manganese(II), cobalt(II)/(III), iron(II)/(III) and nickel(II) complexes of a group of flexible polydentate dihydrazone ligands, based on pyridine-2,6-dipicolinic (A), oxalic (B) and malonic (C) subunits are described. Structural details are reported for the linear dinuclear complexes [Ni2(2poap)2(H2O)2](NO3)4 . 2CH3OH . 2.5H2O (1), [Mn2(pttp)(NO3)2(CH3OH)2(H2O)2](NO3)2 . H2O (2) and [Mn2(mapttp)2(NO3)2(H2O)2](NO3)2 . 10H2O (3), a square tetranuclear complex [Co4(pttp)4]Br6 . 9H2O (4), a tetranuclear tetrahedral complex [Ni4(pttp)6](BF4)6F2 . 14H2O (7), and a mixed spin state tetranuclear Ni(II) complex [(2pyoap)2Ni4(CH3OH)4] . 1.5CH3OH (10), with a diamond-like arrangement of metal ions. The paramagnetic metal centers are well separated in each case, leading to weak antiferromagnetic coupling or non-existent spin exchange.

Journal Article↗
PubMed2004

Antimitogenic effects of HDL and APOE mediated by Cox-2-dependent IP activation.

HDL and its associated apo, APOE, inhibit S-phase entry of murine aortic smooth muscle cells. We report here that the antimitogenic effect of APOE maps to the N-terminal receptor-binding domain, that APOE and its N-terminal domain inhibit activation of the cyclin A promoter, and that these effects involve both pocket protein-dependent and independent pathways. These antimitogenic effects closely resemble those seen in response to activation of the prostacyclin receptor IP. Indeed, we found that HDL and APOE suppress aortic smooth muscle cell cycle progression by stimulating Cox-2 expression, leading to prostacyclin synthesis and an IP-dependent inhibition of the cyclin A gene. Similar results were detected in human aortic smooth muscle cells and in vivo using mice overexpressing APOE. Our results identify the Cox-2 gene as a target of APOE signaling, link HDL and APOE to IP action, and describe a potential new basis for the cardioprotective effect of HDL and APOE.

Animals↗
PubMed2004

[Preventive effect and clinical significance of garlicin injection on mechanical ventilator-associated low respiratory tract deep-seated fungal infection].

OBJECTIVE: To investigate the preventive effect and clinical significance of garlicin injection on ventilator-associated low respiratory tract deep-seated fungal infection (VRFI) as pneumonia. METHODS: Retrospectively analysis on 147 patients underwent mechanical ventilation in our Intensive Care Unit (ICU) in recently 3 years was conducted. According to the garlicin injection administration was used or not, 79 patients with WVUH (West Virgina University Hospital) score > or = 25 points were selected and divided into the preventive group and the control group, and the differences in baseline conditions, incidence of VRFI and hospital outcome between the two groups were compared. RESULTS: There was no significant difference between the two groups in baseline data as age, sex, APACHE II score, SAPS II score and WVUH score. But the incidence of VRFI in the preventive group was significantly lower than that in the control group (P<0.01). The relative risk in the latter was 2.06 (95% CI, 1.25-3.38). No significant difference was found between the two groups in hospital mortality (P>0.05). CONCLUSION: Garlicin injection can effectively reduce the incidence of VRFI, and is inexpensive, it is an ideal prophylactic anti-fungal drug.

Adult↗
PubMed2004

[A cephalometric study of the craniofacial morphology in adult patients with unoperated cleft palate.].

PURPOSE: To evaluate the effects of cleft palate on the craniofacial morphology in adult patients with unoperated cleft palate by cephalometric analysis. METHODS: X-ray cephalometry was used for the study of craniofacial morphology carried out in 7 male and 8 female patients with unoperated cleft palate. Pointing measurements were done with the methods of Downs and Steiner. The data of the cephalometric measurements were compared with that of Guangxi native normal adults by t test. RESULTS: The unoperated cleft palate patient,s SNA,ANS-Ptm(FH) and L1-MP were smaller or shorter than those of normal group while Po-NB was longer. There was significant difference between the two groups (P<0.05 or 0.01). CONCLUSIONS: The deformities of adult patients with unoperated cleft palate were mainly considered to be that the anterior and posterior length of maxilla show hypoplastic while the vertical height of the maxilla the length of anterior cranial fossa and mandible was normal. But the retrusion of alveolar mandible led to chin protrusion.

Adult↗
PubMed2003

Site- and sequence-selective ultrafast hydration of DNA.

Water molecules in the DNA grooves are critical for maintaining structural integrity, conformational changes, and molecular recognition. Here we report studies of site- and sequence-specific hydration dynamics, using 2-aminopurine (Ap) as the intrinsic fluorescence probe and with femtosecond resolution. The dodecamer d[CGCA(Ap)ATTTGCG]2 was investigated, and we also examined the effect of a specific minor groove-binding drug, pentamidine, on hydration dynamics. Two time scales were observed: approximately 1 ps (bulk-like) and 10-12 ps (weakly bound type), consistent with layer hydration observed in proteins and DNA. However, for denatured DNA, the cosolvent condition of 40% formamide hydration is very different: it becomes that of bulk (in the presence of formamide). Well known electron transfer between Ap and nearby bases in stacked assemblies becomes inefficient in the single-stranded state. The rigidity of Ap in the single strands is significantly higher than that in bulk water and that attached to deoxyribose, suggesting a unique role for the dynamics of the phosphate-sugar-base in helix formation. The disparity in minor and major groove hydration is evident because of the site selection of Ap and in the time scale observed here (in the presence and absence of the drug), which is different by a factor of 2 from that observed in the minor groove-drug recognition.

2-Aminopurine↗
PubMed2003

Effect of 1-alkyl-3-methylimidazolium-based ionic liquids as the eluent on the separation of ephedrines by liquid chromatography.

The chromatographic behavior of ephedrines (norephedrine, ephedrine, pseudoephedrine and methylephedrine) on a C18 column was studied with different concentrations of 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquids as the eluent at pH 3.0. The addition of ionic liquid has great effects on the separation of these basic compounds: decreasing band tailing, reducing band broadening, and improving resolution. The retention times of the analytes increase at first and then decrease with the increase in the concentration of ionic liquid. This effect may be attributed to the competition between imidazolium cations and the polar groups of the analytes for the silanol group on the alkylsilica surface, and also to the formation of weak bilayer electronic structure on the C18 column. Several ionic liquids with different alkyl substituents on the imidazolium cations or with different counterions as the eluents were compared.

Borates↗
PubMed2003

Water at DNA surfaces: ultrafast dynamics in minor groove recognition.

Water molecules at the surface of DNA are critical to its equilibrium structure, DNA-protein function, and DNA-ligand recognition. Here we report direct probing of the dynamics of hydration, with femtosecond resolution, at the surface of a DNA dodecamer duplex whose native structure remains unperturbed on recognition in minor groove binding with the bisbenzimide drug (Hoechst 33258). By following the temporal evolution of fluorescence, we observed two well separated hydration times, 1.4 and 19 ps, whereas in bulk water the same drug is hydrated with time constants of 0.2 and 1.2 ps. For comparison, we also studied calf thymus DNA for which the hydration exhibits similar time scales to that of dodecamer DNA. However, the time-resolved polarization anisotropy is very different for the two types of DNA and clearly elucidates the rigidity in drug binding and difference in DNA rotational motions. These results demonstrate that hydration at the surface of the groove is a dynamical process with two general types of trajectories; the slowest of them (approximately 20 ps) are those describing dynamically ordered water. Because of their ultrafast time scale, the "ordered" water molecules are the most weakly bound and are accordingly involved in the entropic (hydration/dehydration) process of recognition.

Animals↗
PubMed2003

Self-assembled dinuclear, trinuclear, tetranuclear, pentanuclear, and octanuclear Ni(II) complexes of a series of polytopic diazine based ligands: structural and magnetic properties.

The nickel coordination chemistry of a series of polytopic diazine (N-N) based ligands has been examined. Self-assembly reactions lead to examples of dinuclear, trinuclear, tetranuclear, pentanuclear, and octanuclear complexes, all of which exhibit magnetic exchange coupling, with antiferromagnetic and ferromagnetic examples. Structural details are presented for [(L1)(2)Ni(2)(H(2)O)(2)](NO(3))(4).3H(2)O (1), [(L2)(2)Ni(3)(H(2)O)(2)](NO(3))(6).8H(2)O (2), [(L3)(4)Ni(4)(H(2)O)(8)] (NO(3))(4).8H(2)O (3), [(L4)(2)Ni(5)(H(2)O)(10)(NO(3))](NO(3))(7).8H(2)O (4), and [(L5)(4)Ni(8)(H(2)O)(8)](BF(4))(8).16H(2)O (5). Compound 1 crystallizes in the monoclinic system, space group P2(1)/c, with a = 14.937(1) A, b = 18.612(2) A, c = 20.583(2) A, beta = 108.862(2) degrees, Z = 4. Compound 2 crystallizes in the orthorhombic system, space group P2(1)2(1)2, with a = 21.771(4) A, b = 13.700(2) A, c = 20.017(3) A, Z = 4. Compound 3 crystallizes in the tetragonal system, space group P4(3), with a = 12.9483(7) A, c = 33.416(3) A, Z = 4. Compound 4 crystallizes in the triclinic system, space group P(-)1, with a = 12.6677(8) A, b = 18.110(1) A, c = 19.998(1) A, alpha = 100.395(1) degrees, beta = 109.514(1) degrees, gamma = 109.686(1) degrees, Z = 2. Compound 5 crystallizes in the monoclinic system, space group P2(1)/n, with a = 21.153(5) A, b = 35.778(9) A, c = 21.823(5) A, beta = 97.757(6) degrees, Z = 4. The linear trinuclear Ni(II) complex (2) has a cis-N-N single bond bridge, and a water bridge linking the central Ni(II) to each external Ni(II) center in each of two similar trinuclear subunits, and exhibits intramolecular ferromagnetic exchange (J = 5.0 cm(-1)). A novel octanuclear metallacyclic ring structure exists in 5, with trans-N-N single bond bridges linking adjacent Ni(II) centers, leading to quite strong intramolecular antiferromagnetic exchange (J = -30.4 cm(-1)).

Journal Article↗
PubMed2003

Self-assembled supramolecular M9 (Mn(II), Fe(III), Zn(II)), M5 (Fe(III)), and [M3]2 (Pb(II)) complexes: structural, magnetic, and Mössbauer properties.

The tritopic ligand 2poap self-assembles in the presence of Zn(NO(3))(2) and Fe(NO(3))(3) to form homoleptic [3 x 3] nonanuclear M(9) (M = Zn(II), Fe(III)) square grid structures and with Pb(ClO(4))(2) to form a dimerized linear trinuclear [Pb(3)](2) structure. Cl2poap and Cl2poapz form self-assembled homoleptic [3 x 3] Mn(II)(9) square grids with Mn(ClO(4))(2) and Mn(NO(3))(2), respectively, but an unusual incompletely metalated Fe(III)(5) square grid is formed on reaction of Cl2poap with Fe(ClO(4))(3). X-ray structures are reported for [Mn(9)(Cl2poap-2H)(6)](ClO(4))(6).10H(2)O (3), [Mn(9)(Cl2poapz-2H)(6)] (NO(3))(6).22H(2)O (4), [Zn(9)(2poap-2H)(3)(2poap-H)(3)](NO(3))(9).24H(2)O (5), [Pb(3)(2poap-2H) (ClO(4))(4)](2).8H(2)O (6), and [Fe(5)(Cl2poap-H)(6)](ClO(4))(9).34.5H(2)O (7). Compound 3 crystallized in the monoclinic system, space group P(-)1, with a = 18.179(1) A, b = 18.857(1) A, c = 25.871(2) A, alpha = 70.506(2) degrees, beta = 86.440(1) degrees, gamma = 75.175(2) degrees, and z = 2. Compound 4 crystallized in the monoclinic system, space group P(-)1, with a = 16.900(2) A, b = 20.02393) A, c = 25.663() A, alpha = 84.743(3) degrees, beta = 84.885(2) degrees, gamma = 67.081(2) degrees, and z = 2. Compound 5 crystallized in the monoclinic system, space group P(-)1, with a = 18.482(1) A, b = 18.774(1) A, c = 28.112(2) A, alpha = 104.020(1) degrees, beta = 97.791(1) degrees, gamma = 117.036(1) degrees, and z = 2. Compound 6 crystallized in the monoclinic system, space group P(-)1, with a = 10.0513(6) A, b = 11.0958(6) A, c = 17.334(1) A, alpha = 100.932(1) degrees, beta = 100.387(1) degrees, gamma = 94.565(1) degrees, and z = 2. Compound 7 crystallized in the monoclinic system, space group P(-)1, with a = 19.164(1) A, b = 19.587(2) A, c = 26.673(2) A, alpha = 76.430(2) degrees, beta = 78.834(2) degrees, gamma = 64.973(1) degrees, and z = 2. Compound 3 exhibits intramolecular antiferromagnetic exchange within the nonanuclear [Mn(9)(mu-O)(12)] grid structure (J = -4.6 cm(-1)), while the analogous nonanuclear complex [Fe(9)(2poap-2H)(6)](NO(3))(15).18H(2)O (8) is dominated by intramolecular antiferromagnetic coupling at high temperatures but exhibits a low-temperature feature indicative of additional ferromagnetic interactions. The isolated pentanuclear Fe(5) [4 + 1] square grid in 7, with distant Fe-Fe bridging, exhibits very weak antiferromagnetic coupling (J = -0.2 cm(-1)). Mössbauer spectroscopy data are consistent with high-spin Fe(III)(9) and Fe(III)(5) structures.

Journal Article↗
PubMed2003

Differential proliferative response in the postischemic hippocampus, temporal cortex, and olfactory bulb of young adult macaque monkeys.

We investigated the fate of proliferating cells in the adult monkey brain after global ischemia. We used the thymidine analogue bromodeoxyuridine (BrdU) to label S-phase cells and their progeny in Japanese macaques subjected to global cerebral ischemia for 20 min or to a sham operation. Subsequently, newly generated cells were identified by BrdU immunohistochemistry, and their immunophenotype was determined quantitatively, using specific markers. The ischemic insult significantly increased the number of proliferating cells in the hippocampus and temporal neocortex, where the majority BrdU-labeled cells expressed markers for microglia (Iba1, CD68, and Ham56) or astrocytes (S-100beta and glial fibrillary acidic protein [GFAP]). In contrast, the proliferation level in the parahippocampal region remained unchanged. This discrepancy prompted us to investigate the postischemic response in the olfactory bulb, a well-known site of adult cell generation that is anatomically distant from the above-mentioned regions but that is also subjected to the global ischemic insult. The olfactory bulb contained clusters of proliferating cells expressing markers for neural (Musashi1 and Nestin) and/or neuronal (class III beta-tubulin) progenitors; these were immunophenotypically distinct from other cell types. Their number and distribution were unaltered by ischemia. Our results demonstrate that cell proliferation and differentiation in the adult macaque brain and olfactory bulb are differentially affected by a common insult.

Animals↗
PubMed2003

Proliferation of neural and neuronal progenitors after global brain ischemia in young adult macaque monkeys.

To investigate the effect of global cerebral ischemia on brain cell proliferation in young adult macaques, we infused 5-bromo-2'-deoxyuridine (BrdU), a DNA replication indicator, into monkeys subjected to ischemia or sham-operated. Subsequent quantification by BrdU immunohistochemistry revealed a significant postischemic increase in the number of BrdU-labeled cells in the hippocampal dentate gyrus, subventricular zone of the temporal horn of the lateral ventricle, and temporal neocortex. In all animals, 20-40% of the newly generated cells in the dentate gyrus and subventricular zone expressed the neural progenitor cell markers Musashi1 or Nestin. A few BrdU-positive cells in postischemic monkeys were double-stained for markers of neuronal progenitors (class III beta-tubulin, TUC4, doublecortin, or Hu), neurons (NeuN), or glia (S100beta or GFAP). Our results suggest that ischemia activates endogenous neuronal and glial precursors residing in diverse locations of the adult primate central nervous system.

Animals↗
PubMed2003

Prosthetic disc nucleus (PDN) replacement for lumbar disc herniation: preliminary report with six months' follow-up.

A clinical follow-up study was performed to evaluate lumbar disc nucleus replacement clinically and functionally. The objective was to assess the clinical efficacy of the prosthetic disc nucleus (PDN) for treatment of lumbar disc herniation. The PDN was designed to treat patients suffering from disc herniation and/or degeneration. Clinical trials for PDN were first conducted in 1996, and the results showed that the PDN device was effective in most of the patients who were implanted. These studies had been carried out with patients who were implanted with a pair of the devices. The main complication was device migration. Therefore, a follow-up study based on a single PDN device implantation was designed to evaluate its clinical result. Forty-five patients with lumbar disc herniation were implanted with one PDN device from March 2002 to December 2002. Thirty (66.7%) patients came to the clinical, functional, and radiographic 6-month follow-up examinations. Independent analysis was performed by careful review of the charts, operative notes, preoperative and postoperative radiographs, magnetic resonance images, and follow-up records of all patients. After implantation, significant proportions of patients experienced pain relief. Improvements were noted in pain intensity, walking distance, lumbar mobility, neurologic weakness, Oswestry and Prolo scores, and intervertebral disc height. No difference in work status after PDN implantation could be detected. Compared with the preoperative height, the intervertebral disc had gained 19.7% (P < 0.001). Device migration, failure, and dislocation were not noticed in any patient. A few patients had minor complications such as transient low-grade fever. Clinically, a single PDN is preferred and can effectively increase the height of the intervertebral disc in patients with lumbar disc herniation. However, long-term follow-up of PDN implantation needs to be studied.

Adult↗
PubMed2003

A network of coupled chaotic maps for adaptive multi-scale image segmentation.

In this paper, a network of coupled chaotic maps for multi-scale image segmentation is proposed. Time evolutions of chaotic maps that correspond to a pixel cluster are synchronized with one another, while this synchronized evolution is desynchronized with respect to time evolution of chaotic maps corresponding to other pixel clusters in the same image. The number of pixel clusters is previously unknown and the adaptive pixel moving technique introduced in the model makes it robust enough to classify ambiguous pixels.

Animals↗
PubMed2003

[Concentration of follistatin in maternal serum at term and its expression in placenta].

OBJECTIVE: To investigate the possible origin and role of follistatin (FS) in pregnancy. METHODS: The maternal serum FS levels in menstrual cycle, first trimester (8 - 12 weeks) and term (38 - 41 weeks) were determined by a specific two-site enzyme-linked immunosorbent assay (ELISA). Reverse transcription-polymerase chain reaction (RT-PCR) method was utilized to semi-quantitatively determine FS mRNA levels in the ovaries and placentas. RESULTS: Maternal serum FS level at term was significantly higher than that in the first trimester of pregnancy and that in normal women during the menstrual cycle (180 +/- 26) micro g/L, (4.4 +/- 2.1) micro g/L, (1.5 +/- 2.2) micro g/L, (respectively P < 0.001). Both placentas and ovaries expressed FS mRNA. Semi-quantitative RT-PCR showed that the expression levels of FS mRNA in placenta were higher than that in ovary of same period, but lower than that in ovary of menstrual phase (0.8 +/- 0.4, 0.4 +/- 0.3, 0.93 +/- 0.13, respectively P < 0.05). CONCLUSION: Fetal-placental unit may be the major source of maternal serum FS. The relatively higher levels of FS in the placentas at term may reflect important roles in modulating the development of embryo and the function of placenta.

Adult↗
PubMed2003

[Study on the relationship between activin A, follistatin and preeclampsia].

OBJECTIVE: The purpose of this study was to determine the relationship of maternal serum activin A, follistatin and their mRNA expression in placenta with preeclampsia at term. METHODS: Twenty women with preeclampsia were enrolled in this study. Twenty healthy pregnancies matched for gestational ages were recruited as control group. Maternal serum activin A and follistatin in two groups were compared by using enzyme linked immunosorbent assay (ELISA). Placental tissues were obtained from preeclampsia and healthy control groups for analysis of activin A mRNA and follistatin mRNA expression by using quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). Linear correlation analysis was used to explore the relationship between placental avtivin A mRNA and maternal serum activin A concentrations. RESULTS: (1) Maternal serum concentrations of activin A are significantly increased in preeclampsia group (33.7 +/- 6.6) micro g/L compared with control group (9.9 +/- 2.1) micro g/L (P < 0.01). Maternal serum follistatin levels were not different between preeclampsia group (5.1 +/- 0.6) micro g/L and control group (4.7 +/- 0.3) micro g/L (P > 0.05). (2) The placentas of preeclampsia group expressed activin A mRNA levels at significantly higher levels 1.11 +/- 0.21 than that of control group 0.61 +/- 0.17 (P < 0.01). The expression of follistatin mRNA were not different between preeclampsia group 0.57 +/- 0.31 and control group 0.54 +/- 0.27 (P > 0.05). (3) In preeclampsia and control groups, maternal serum activin A concentrations had a significant positive correlation with activin A mRNA expression in placentas (r = 0.89, P < 0.01). CONCLUSION: These results suggest that activin A is increased in women with preeclampsia, the elevated levels of activin A due to increased placental production.

Activins↗
PubMed2002

Vitamin B6 protects primate retinal neurons from ischemic injury.

Vitamin B6 derivatives protect the retinal neurons from excitotoxic injury in vitro. However, their in vivo role in a process involving excitotoxicity, such as ischemia, remains unknown. We studied potential protective effects of pyridoxal 5'-phosphate (PLP) and pyridoxal hydrochloride (pyridoxal) on the retinal neurons in a monkey model of transient global ischemia. Daily intravenous injections (15 mg/kg) of pyridoxal and PLP were performed for consecutive 10 days. On the sixth day, whole brain complete ischemia was produced by clipping the innominate and the left subclavian arteries for 20 min. The monkeys were sacrificed 5 days after ischemia and their retinas were processed for histological analysis. The ischemia induced a marked cellular injury in the retina as shown by the loss of ganglion cells and the reduction of thickness of the ganglion cell, inner plexiform, and inner nuclear layers. PLP significantly prevented the ganglion cell loss and the reduction of thickness of the ganglion cell layer. Pyridoxal significantly prevented the ganglion cell loss as well as the reduction of thickness of ganglion cell, inner plexiform and inner nuclear layers. These results suggest that PLP and pyridoxal counteract the postischemic neuronal death in the adult primate retina, offering a potential for a novel pharmacotherapy of retinal ischemic injury.

Animals↗