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Biomedical subjects

M Shang

Publications and source records attributed to M Shang.

At least 19 recordsLinked to original sources
PubMed2001

A new stabilised form of isobenzofuran, rack-mounted on an alicyclophane.

New stable, crystalline isobenzofurans 9a and 9b linked through the 1,3-positions and incorporated into alicyclophanes have been prepared from the related furanoalicyclophane 5 in three steps (i) addition of benzyne or 4,5-bis(trimethylsilyl)benzyne (ii) hydrogenation of the pi-bond (iii) ejection of ethylene by flash vacuum pyrolysis, and shown to yet retain high 1,3-diene character and form adducts with dienophiles, e.g. dimethyl acetylenedicarboxylate or N-methyl maleimide; the corresponding off-rack 1,3-dimethylisobenzofurans were too unstable for isolation.

Journal Article↗
PubMed2001

The LG3 module of laminin-5 harbors a binding site for integrin alpha3beta1 that promotes cell adhesion, spreading, and migration.

Laminins are a family of extracellular matrix glycoproteins involved in cell adhesion and migration. A major obstacle to understanding their structure-function relationships is the lack of small laminin domains capable of replicating integrin-binding, cell-adhesive, and migratory functions of the intact molecule. Here, we show that the recombinant LG3 (rLG3) module (26 kDa) of laminin-5 (Ln-5) alpha(3) chain replicated key Ln-5 activities. rLG3 but not rLG1 or rLG2 supported cell adhesion and migration of at least two distinct cell lines, in an integrin alpha(3)beta(1)-dependent manner. Cell adhesion to rLG3 was regulated by divalent cations and accompanied by cell spreading and tyrosine phosphorylation of FAK focal adhesion kinase. The integrin binding activity of rLG3 was confirmed by rLG3 affinity chromatography of detergent cell lysates, which resulted in specific purification of integrin alpha(3)beta(1). To our knowledge, this is the first report directly demonstrating that a recombinant laminin LG module is an active domain capable of supporting integrin-dependent cell adhesion and migration.

Amino Acid Sequence↗
PubMed2001

[Changes in respiratory and circulatory function during sequential invasive-noninvasive mechanical ventilation].

OBJECTIVE: To investigate the change of respiratory and circulatory function in COPD during sequential invasive-noninvasive mechanical ventilation. METHODS: 12 COPD patients with type II respiratory failure were ventilated via endotracheal intubation. When pulmonary infection was under control (the appearance of "PIC Window"), all patients were extubated and received mask ventilation. The parameters of hemodynamics oxygenation and esophageal pressure were measured during endotracheal ventilation and mask ventilation (3 hrs after extubation). RESULTS: The change of respiratory and circulatory parameters were not significantly different between invasive mechanical ventilation and noninvasive mechanical ventilation (P > 0.05). CONCLUSION: The respiratory and circulatory function of COPD patients remained stable during sequential invasive-noninvasive mechanical ventilation.

Adult↗
PubMed2001

Efficacy of continuous tracheal gas insufflation in spontaneously breathing canine with acute lung injury.

OBJECTIVE: To investigate the effects of continuous tracheal gas insufflation (CTGI) combined with biphasic intermittent positive airway pressure (BIPAP) ventilation on dogs with spontaneous breathing. METHODS: Eight canine models with oleic acid induced lung injury and spontaneous breathing were ventilated in a random order by Evita 2 (Drager Inc., Germany) in modes of BIPAP (BIPAP group) and BIPAP with CTGI flow rate of 3, 6 and 9 L/min (T3, T6 and T9 groups), respectively. The setting parameters of BIPAP were fiction of inspired oxygen 60%, inspiratory to expiratory ratio 1:1, respiratory rate 20 and positive end expiratory pressure 5 cm H2O. Arterial and mixed venous blood gas, lung mechanics, systemic and pulmonary hemodynamics status were monitored at the same level of PaCO2 obtained by adjusting peak inspiratory pressure of BIPAP. RESULTS: Peak inspiratory pressure in the T6 group (14 +/- 4 cm H2O) and in the T9 group (11 +/- 3 cm H2O) were significantly lower than that of BIPAP (20 +/- 5 cm H2O, P < 0.01), but there was no significant difference among the T3, T6 and T9 groups or between the T3 and BIPAP groups. PaO2, mean artery blood pressure, mean pulmonary artery pressure, pulmonary artery wedge pressure, cardiac output, oxygen delivery and oxygen consumption all remained unchanged in four different conditions. CONCLUSIONS: Using BIPAP combined with CTGI does not cause asynchrony between ventilator and spontaneous breathing, but significantly decreases airway pressure with no influence on hemodynamics and oxygenation. Therefore, BIPAP with CTGI may be a useful support technique, especially in cases where the airway pressure should be limited.

Animals↗
PubMed2000

Role of the transition metal in metallaborane chemistry. Reactivity of (Cp*ReH2)2B4H4 with BH3.thf, CO, and Co2(CO)8.

The reaction of Cp*ReCl4, [Cp*ReCl3]2, or [Cp*ReCl2]2 (Cp* = eta 5-C5Me5) with LiBH4 leads to the formation of 7-skeletal-electron-pair (7-sep) (Cp*ReH2)2(B2H3)2 (1) together with Cp*ReH6. Compound 1 is metastable and eliminates H2 at room temperature to generate 6-sep (Cp*ReH2)2B4H4 (2). The reaction of 2 with BH3.thf produces 7-sep (Cp*Re)2B7H7, a hypoelectronic cluster characterized previously. Heating of 2 with 1 atm of CO leads to 6-sep (Cp*ReCO)(Cp*ReH2)B4H4 (3). Both 2 and 3 have the same bicapped Re2B2 tetrahedral cluster core structure. Monitoring the reaction of 2 with CO at room temperature by NMR reveals the formation of a 7-sep, metastable intermediate, (Cp*ReCO)(Cp*ReH2)(B2H3)2 (4), which converts to 3 on heating. An X-ray structure determination reveals two isomeric forms (4-cis and 4-trans) in the crystallographic asymmetric unit which differ in geometry relative to the disposition of the metal ancillary ligands with respect to the Re-Re bond. The presence of these isomers in solution is corroborated by the solution NMR data and the infrared spectrum. In both isomers, the metallaborane core consists of fused B2Re2 tetrahedra sharing the Re2 fragment. On the basis of similarities in electron count and spectroscopic data, 1 also possesses the same bitetrahedral structure. The reaction of 2 with CO2(CO)8 results in the formal replacement of the four rhenium hydrides with a 4-electron CO2(CO)5 fragment, thereby closing the open face in 2 to produce the 6-sep hypoelectronic cluster (Cp*Re)2CO2(CO)5B4H4 (5). These reaction outcomes are compared and contrasted with those previously observed for 5-sep (Cp*Cr2)2B4H8.

Journal Article↗
PubMed2000

An integrated approach to the mid-spin state (S = 3/2) in six-coordinate iron(III) chiroporphyrins.

An intermediate-spin state very close to the mid-spin state (S = 3/2) can be stabilized in a ferric porphyrin by an integrated approach which combines the favorable effects of a weak axial field strength and of a small macrocycle hole. Axial ligand exchange by reaction of chloroiron(III)tetramethylchiroporphyrin [(TMCP)FeCl] with silver perchlorate in ethanol-chloroform leads to ethanol-ligated ferric chiroporphyrins. Two distinct crystalline products containing a bisethanol complex [[(TMCP)FeIII(EtOH)2]ClO4] and three variants of a mixed ethanol-water complex [[(TMCP)FeIII(EtOH)(H2O)]ClO4] have been structurally characterized in the solid state. The small hole of the ruffled chiroporphyrin and the weak axial oxygen ligation result in strongly tetragonally distorted complexes. The six-coordinate species exhibit long axial Fe-O bond distances (2.173(5)-2.272(4) A) and the shortest equatorial Fe-N(av) distances (1.950(5)-1.978(7) A) found as yet in a ferric porphyrin, reflecting a singly occupied dz2 orbital and a largely depopulated dx2-y2 orbital. An intriguing case of bond-stretch isomerism is seen for the axial Fe-O bonds in two crystallographically independent mixed ethanol-water species, and it is accounted for by their distinct intra- and intermolecular hydrogen-bond arrays. The Mössbauer spectrum (delta = 0.35(1) mm s-1 and delta EQ = 3.79(1) mm s-1 at 77 K) indicates a strong tetragonal distortion around the ferric ion, in agreement with the structural data. The value of the magnetic moment (mu eff = 3.8 mu B in the range 50-300 K) strongly supports a mid-spin state (S = 3/2). The EPR spectrum at 80 K (g perpendicular approximately 4.0, g parallel approximately 2.00) is consistent with a nearly pure mid-spin state (4A2) with little rhombic distortion. The 1H NMR spectra in CDCl3-EtOH exhibit upfield-shifted resonances for the pyrrole protons (delta approximately -30 ppm) which are consistent with the depopulated iron dx2-y2 orbital. Solution equilibria with water and various alcohols, and the spin state of the corresponding species, are discussed on the basis of the NMR data. The bisethanol and ethanol-water species are potential models of unknown hemoprotein ligation states such as Tyr(OH)/Tyr(OH) or Tyr(OH)/H2O that could be obtained by site-directed mutagenesis.

Journal Article↗
PubMed2000

Fine-tuning of metallaborane geometries: chemistry of iridaboranes derived from the reaction of

From reaction of [(Cp*Ir)2HxCl(4-x)] (x=1, 0) and LiBH4, arachno-[[Cp*IrH2]B3H7](1) is produced in moderate yield concurrently with [Cp*IrH4]. In contrast, reaction of [(Cp*Ir)2H2Cl2] with LiBH4 results in arachno-[[Cp*IrH]2(mu-H)B2H5] (3) in high yield at room temperature but a mixture of 1 and [[Cp*IrH]2(mu-H)BH4] (2) at 0 degrees C. BH3 x THF converts 1 to arachno-[(Cp*IrHB4H9] (4) and 2 to 3 with 1 as a minor product. Further, reaction of 3 with excess of BH3 x THF results in formation of nido-[[Cp*Ir]2-(mu-H)B4H7] (6) formed by loss of H2 from the intermediate arachno-[[Cp*IrH]2B4H8] (5). Reaction of 1 with [Co2(CO)8] permits the isolation of two metallaboranes, arachno-[[Cp*Ir(CO)]-B3H7] (7) and nido-[1-[Cp*Ir]-2,3-Co2-(CO)4(mu-CO)B3H7] (8). Treatment of 4 with [Co2(CO)8] gives only one single mixed-metal metallaborane nido-[1-[Cp*Ir]-2-Co(CO)3B4H7 (9) in high yield. Finally, pyrolysis of 8 results in loss of hydrogen and formation of pileo-[1-[Cp*Ir]-2,3-Co2(CO)5B3H5] (10) with a BH-capped square-pyramidal structure. With kinetic control rational synthesis of a variety metallaboranes has been achieved by varying the number of chlorides in the monocyclopentadienylmetal halide dimer, reaction temperature, types of monoborane, and metal fragment sources.

Journal Article↗
PubMed2000

Molecular structure of an Fe(IV) species:.

The molecular structure of the formal iron(IV) porphyrinate derivative, [[Fe(TTP)]2N]SbCl6 (TTP = tetratolylporphyrinate), is reported. The structural parameters are compared to the previously reported species [Fe(TPP)]2N, in which the iron oxidation state is +3.5. Both the equatorial and axial bond distances in [[Fe(TTP)]2N]SbCl6 are slightly shortened and consistent with an increased formal charge on iron. The value for the axial Fe-N distance is 1.6280(7) A, and the average value of the equatorial Fe-Np distances is 1.979(5) A. The Mössbauer isomer shift decreases upon oxidation, again consistent with an increase in formal charge. Values for the isomer shift at room temperature are -0.13 mm/s for [[Fe(TTP)]2N]SbCl6 and 0.04 mm/s for [Fe(TTP)]2N. Crystal data for [[Fe(TTP)]2N]SbCl6 are as follows: orthorhombic, space group Fddd, Z = 8, a = 23.689(2) A, b = 31.056(3) A, c = 22.7788(18) A.

Crystallography, X-Ray↗
PubMed2000

Iron complexes of the cardioprotective agent dexrazoxane (ICRF-187) and its desmethyl derivative, ICRF-154: solid state structure, solution thermodynamics, and DNA cleavage activity.

This study investigates the solution thermodynamics of the iron complexes of dexrazoxane (ICRF-187, (+)-1,2-bis(3,5-dioxopiperazinyl-1-yl)propane), [Fe(ADR-925)](+/0), and its desmethyl derivative ICRF-154, [Fe(ICRF-247)H2O](+/0). The solid state structure of [Fe(ICRF-247)H2O]+ is also reported. [Fe(ICRF-247)H2O]Br x 0.5NaBr x H2O crystallizes in the P42(1)2 space group with Z = 4, a = 14.9851(8), b = 14.9851(8), c = 8.0825(9) A and R = 0.03(2) for 1839 reflections and exhibits a pentagonal bipyramidal geometry with a labile water molecule occupying the seventh coordination site. Potentiometric titrations (FeL = 8.5 mM, 0.1 M NaNO3, 25 degrees C) reveal stable monomeric complexes (log Kf = 18.2 +/- 0.1, [Fe(ADR-925)]+, and 17.4 +/- 0.1, [Fe(ICRF-247)H2O]+) exist in solution at relatively low pH. Upon addition of base, the iron-bound water is deprotonated; the pKa values for [Fe(ICRF-247)H2O]+ and [Fe(ADR-925)]+ are 5.63 +/- 0.07 and 5.84 +/- 0.07, respectively. At higher pH both complexes undergo mu-oxo dimerization characterized by log Kd values of 2.68 +/- 0.07 for [Fe(ICRF-247)H2O]+ and 2.23 +/- 0.07 for [Fe(ADR-925)]+. In the presence of an oxidant and reductant, both [Fe(ICRF-247)H2O]+ and [Fe(ADR-925)]+ produce hydroxyl radicals that cleave pBR322 plasmid DNA at pH 7 in a metal complex concentration-dependent manner. At low metal complex concentrations (approximately 10(-5) M) where the monomeric form predominates, cleavage by both FeICRF complexes is efficient while at higher concentrations (approximately 5 x 10(-4) M) DNA cleavage is hindered. This change in reactivity is in part accounted for by dimer formation.

Cardiovascular Agents↗
PubMed2000

mu-Oxo-bis[(2,3,12,13-tetrabromo-5,10,15, 20-tetraphenylporphyrinato)iron(III)] bis(dichloromethane) solvate.

The precise structure of the title compound, [Fe(2)O(C(44)H(24)Br(4)N(4))(2)].2CH(2)Cl(2), is reported. The Fe-N distances are non-equivalent in pairs because of the asymmetric peripheral substitution; the values are 2.098 A to the brominated rings and 2.041 A to the other two rings. The Fe-O bond distance is 1.7583 (4) A. The molecule has required twofold symmetry so that there is one unique porphyrin macrocycle and one Fe-O bond length in contrast to a previous report on the same species.

Crystallography, X-Ray↗
PubMed2000

[Sequential non-invasive following short-term invasive mechanical ventilation in COPD induced hypercapnic respiratory failure].

OBJECTIVE: To estimate the feasibility and the efficacy of early extubation and sequential non-invasive mechanical ventilation(MV) in COPD with exacerbated hypercapnic respiratory failure. METHODS: 22 intubated COPD cases with severe hypercapnic respiratory failure due to pulmonary infection (pneumonia or purulent bronchitis) were involved in the study. At the time pulmonary infection had been significantly controlled (resolution of fever and decrease in purulent sputum, radiographic infiltrations, and leukocytosis. We call the time as "Pulmonary Infection Control Window", PIC window) after the antibiotic and the comprehensive therapy, the early extubation was conducted and followed by non-invasive MV via facial mask immediately in 11 cases (study group). Other 11 COPD cases with similar clinical characteristics who continuously received invasive MV after PIC window were used as control group. RESULTS: The groups had similar clinical characteristics and gas exchange, initially and at the time of PIC window. For study group and control group, the duration of invasive MV was (7.1 +/- 2.9) vs (23.0 +/- 14.0) days, P < 0.01; the total duration of ventilatory support was (13 +/- 7) vs (23 +/- 14) days, P < 0.05; the incidence of VAP were 0/11 vs 6/11, P < 0.01; the duration of ICU stay was (13 +/- 7) vs (26 +/- 14) days, P < 0.05, respectively. CONCLUSIONS: In COPD patients requiring intubation and MV for pulmonary infection and hypercapnic respiratory failure, early extubation followed by non-invasive MV initiated at the point of PIC window may significantly decrease the invasive and total durations of ventilatory support, the risk of VAP, and the duration of ICU stay.

Aged↗
PubMed2000

[Effects of continuous tracheal gas insufflation during biphasic intermittent positive airway pressure ventilation on canine model of acute lung injury with spontaneous breathing].

OBJECTIVE: To study the possibility of using continuous tracheal gas insufflation (CTGI) in dogs with spontaneous breathing. METHODS: Eight canine with oleic acid induced lung injury which had spontaneous breathing were ventilated by Evita 2 (Drager Inc). The setting parameters were FiO(2) (60%), I/E (1:1), RR (20) and PEEP (5 cm H(2)O) in four different conditions: BIPAP (BIPAP group) and BIPAP with different CTGI flow rates (3, 6 and 9 L/min, T3, T6 and T9 group). Gas exchange, lung mechanics and hemodynamic status were monitored at the same level of PaCO(2) obtained by adjusting the high pressure (P high) of BIPAP. RESULTS: The peak inspiratory pressures in the T6 group (14 cm H(2)O +/- 4 cm H(2)O) and T9 group (11 cm H(2)O +/- 3 cm H(2)O) were significantly lower than that of BIPAP group (20 cm H(2)O +/- 5 cm H(2)O, P < 0.01), but significant differences were not found neither among T3, T6 and T9 groups, nor between T3 and BIPAP groups. PaO(2), hemodynamics and oxygenation remained unchanged in the four different conditions. CONCLUSION: BIPAP combined with CTGI in canine with spontaneous breathing could significantly decrease the airway pressure, with no influence on hemodynamics and oxygenation. Thus BIPAP with CTGI may be a useful support technique, especially for cases whose airway pressure should be limited.

Animals↗
PubMed1999

[Continuous tracheal gas insufflation during pressure control ventilation with a pressure relief valve].

OBJECTIVE: To establish the method of continuous tracheal gas insufflation (CTGI) and investigate the role of pressure relief valve (PRV) in limiting high peak airway pressure induced by CTGI. METHODS: CTGI device was made by authors. Nine healthy mongrel dogs were mechanically ventilated by using Evita 2 (Drager Inc.). PRV was inserted into the ventilatory circuit for selected experiment steps and adjusted a threshold pressure equal to the preset inspiratory pressure. PCV, PCV + CTGI (TGI group) and PCV + CTGI + PRV (PRV group) were conducted in different inspiration/expiration (I/E) ratio of 1:2 and 2:1. Gas exchange, lung mechanics and hemodynamics status were monitored at the constant set inspiratory pressure of PCV. RESULTS: At the same I/E ratio, peak airway pressure in TGI group was higher than that of PRV and PCV group (P < 0.01), whereas PRV group maintained the preset inspiratory pressure as PCV group. At the different I/E ratio, peak airway pressure in TGI (2:1) group was higher than that of TGI (1:2) group(P < 0.01). PaCO2 in TGI and PRV group decreased significantly than that of PCV, TGI group was more lower than PRV group, PaO2, hemodynamics and oxygenation remained unchanged in all groups. CONCLUSIONS: The CTGI device is effective in improving alveolar ventilation with no significant influence on hemodynamics and oxygenation; A pressure relief valve is necessary to ensure the safe use of CTGI.

Animals↗
PubMed1999

[Studies on identification of yinchaihu by UV and IR].

OBJECTIVE: To study the identification of nine species of Yinchaihu derived from four genera of Caryophyllaceae, namely, Stellaria dichotoma var. lanceolata, St. dichotoma var. dichotoma, Arenaria juncea, A. capillaris var. glandulifera, Silene fortunei, Si. jenisseensis, Gypsophila pacifica, G. oldhamiana and G. licentiana. METHOD: UV and IR of alcohol extraction. RESULTS: The UV and IR spectra of these 9 plant roots have some difference. CONCLUSION: St. dichotoma var. lanceolata specified in the Chinese Pharmacopoeia can be distinguished from the other plants and all these 4 genera can be differentiated from one another by both UV and first derivative spectra. The genus Stellaria can be identified from the other 3 genera by IR.

Caryophyllaceae↗
PubMed1998

[Studies on flavonoids from Fenugreek (Trigonella foenumgraecum L.)].

OBJECTIVE: To study the flavonoids in fenugreek (Trigonella foenumgraecum) produced in China. METHOD: The flavonoids were isolated with silica gel, polyamide and Sephadex LH-20 chromatography, and their structures were identified by physical, chemical properties and spectral analysis. RESULT: Five flavonoid compounds were isolated from fenugreek seeds and identified as vitexin, tricin, naringenin, quercetin and tricin-7-O-beta-D-glucopyranoside. CONCLUSION: Three flavonoids, tricin, naringenin and tricin-7-O-beta-D-glucopyranoside, were isolated from fenugreek as well as from the plants of Trigonella for the first time.

Apigenin↗
PubMed1998

[The inhibitory effect of antisense--RNA of papillomavirus type 16 E6E7 genes on malignant phenotypes of cervical carcinoma cell line].

In our previous study, the malignant phenotypes of the NIH3T3 cells, transformed with HPV-16 E6E7 genes, could be inhibited by the antisense RNA of HPV-16 E6E7. In this study, the antisense RNA of HPV-16 E6E7 was induced into the cervical carcinoma cells, caski, which contained HPV-16 DNA. The results showed that the cellular growth velocity was down regulated by the antisense RNA of HPV-16 E6E7, the ability of forming cellular colonies in soft agar medium and the tumorigenicity in nude mice of CaSki cells were also inhibited by the antisense cellular colonies in soft agar median and the tumorigenicity in nude mice of Caski cells were also inhibited by the antisense RNA. In addition, the decrease of the expression of viral early genes in carcinoma cells was detected with Western blot assay. It denoted that the phenotypes and the carcinogenicity of tumor cells were inhibited by the associated antisense RNA, and this may be one of the pathways inducing tumor cells reversion.

Animals↗