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Biomedical subjects

B Mao

Publications and source records attributed to B Mao.

At least 37 records · Page 2Linked to original sources
PubMed1999

[The effect of cyclooxygenase-2 inhibitor on acute lung injury].

OBJECTIVE: To investigate changes of cyclooxygenase-2 (COX-2) mRNA expression and intervention effect of selective cyclooxygenase-2 inhibitor Meloxicam on acute lung injury (ALI). METHODS: We measured COX-2 mRNA expression by reverse-transcription polymerase chain reaction in rat lung with ALI induced by lipopolysaccharide, and observed changes of prostaglandins (PGs), PaO2 and histopathology. RESULTS: Resting rat lung expressed a little COX-2 mRNA; expression of cyclooxygenase-2 mRNA was up-regulated significantly in the lung after rats were injured by LPS. Selective COX-2 inhibitor Meloxicam alleviated histopathologic damage in the lung, inhibited production of PGs and attenuated PaO2 decline. CONCLUSIONS: COX-2 is a main isoform responsible for enhancing PGs production during ALI. Meloxicam can inhibit activity of COX-2 and may be useful in the treatment of ALI.

6-Ketoprostaglandin F1 alpha↗
PubMed1999

[The role of apoptosis and Fas/FasL in lung tissue in patients with acute respiratory distress syndrome].

OBJECTIVE: To evaluate the effects of apoptosis and expression of apoptotic related genes on acute respiratory distress syndrome (ARDS). METHODS: Nine patients with ARDS and 5 non-ARDS patients were included. By using TUNEL, histopathology and immunocytochemistry techniques, apoptosis and Fas, FasL protein expression were studied in patients with ARDS in acute stage and in control subjects. RESULTS: Apoptosis ratio was significantly higher in lung tissues in the patients with ARDS than in those of control subjects, especially in alveolar epithelial cells and pulmonary vascular endothelial cells. Fas, FasL protein expression were up-regulated in lung tissues of patients with ARDS. There was a significant correlation between expression of Fas, FasL and ratio of apoptosis. CONCLUSIONS: During the acute stage of ARDS, increase of apoptosis ratio in alveolar epithelial cells and pulmonary vascular endothelial cells, and activation of Fas/FasL system may contribute to the pathogenesis of this syndrome.

Adult↗
PubMed1999

[Clinical study on relationship of blood stasis syndrome with plasma endothelin and nitric oxide changes in acute pancreatitis patients].

OBJECTIVE: To study the relationship of blood stasis Syndrome with plasma endothelin (ET) and nitric oxide (NO) in acute pancreatitis patients. METHODS: A healthy control group and three groups of patients with three different Syndromes of TCM were established. Patients' ET and NO were determined by radioimmunoassay and reversed-phase high performance liquid chromatography respectively before and after treatment. The NO level was represented by the sum of NO2 and NO3. RESULTS: ET and ET/NO ratio were not changed significantly in patients with Liver-Spleen Qi Stagnant Syndrome, but increased significantly in patients with Liver-Spleen Damp-Heat Syndrome or with Spleen Stomach excessive Heat Syndrome (P < 0.05 or P < 0.01). CONCLUSION: ET and ET/NO ratio might be the important objective markers of the existence of blood stasis Syndrome in acute pancreatitis patients.

Acute Disease↗
PubMed1999

[Systemic inflammatory response syndrome in critical patients - an analysis of 1,292 cases].

OBJECTIVE: To study the significance of the occurrence and the development of systemic inflammatory response syndrome (SIRS) in critical patients. METHODS: The clinical data of 1292 patients accepted by our hospital in ten months from October 1995 to July 1996 were analyzed. The patients met at least two of the criteria for SIRS such as fever, hypothermia, tachycardia, tachypnea or abnormal white blood cell count. RESULTS: 1292 (67.7%) of the 1909 patients investigated met two or more of the criteria for SIRS. In the 1292 cases, those who met two, three or four of the criteria were respectively 467 (36.1%), 526 (40.7%) and 299 (23.1%). 149 patients (11.5%) in the 1292 cases died of multiple organ dysfunction syndrome (MODS). In which 33 (7.1%), 57 (10.8%) and 59 (19.7%) respectively in patients with two, three and four of the criteria for SIRS. The proportion of patients suffering from acute respiratory distress syndrome, metabolic function dysfunction, disseminated intravascular coagulation and acute renal failure increased with the increase in the number of SIRS criteria that the patients met and with the increase in the proportion of patients progressing from SIRS to septic shock. The mortality rate of the patients also gradually increased while the patients with SIRS were developing sepsis, severe sepsis and septic shock, but there was no statistical significance (P > 0.05). CONCLUSION: It is suggested that bacterial infection, severe trauma and acute pancreatitis might cause SIRS and compensatory anti-inflammatory response syndrome might play an important role in the maintenance of internal environment of the body. A comprehensive understanding of SIRS might be of help to the management of critical diseases.

Adolescent↗
PubMed1999

[Treatment of complex crainocervical junction malformation by transoccipito-cervical posterolateral approach].

OBJECTIVE: To report the treatment of six patients suffering from complex craniocervical junction (CCJ) malformation by transoccipitocervical posterolateral approach which is a new surgical method. METHODS: Transoccipitocervical posterolateral approach was confirmed feasible by anatomy of the body. Diagnosis was made sure CT-three dimensional image and MRI for every patient. All cases reaived odontoidectomy and suboccipital decompression and/or bone graft. RESULTS: All patients showed favorable outcome without deterioration or recurrence. Six patients were followed up for 15 - 10 months. All patients showed marked progressive improvement of neurological disturbances and three of them resumed work half a year after operation. CONCLUSION: Transoccipitocervical posterolateral approach is a new surgical procedure by which anterior and posterior decompression of foramen magnun aria and bone graft (posterior craniocervical stabilization) could be fulfilled during one operation.

Adult↗
PubMed1999

[Expression of vascular endothelial growth factor in brain astrocytoma and its clinical evaluation].

Angiogenesis is often involved in tumor growth. Neovascularization plays an important role in the prognosis of patients with brain astrocytoma. Vascular endothelial growth factor (VEGF) has been known as the potent angiogenetic factor and mitogen. To gain a deep insight into the possible relation between expression of VEGF and pathological characterization/prognosis in brain astrocytoma, the authors investigated 107 cases of brain astrocytoma and 25 cases of normal brain, tissue via a combination of immunohistochemical staining of paraffin-embedded tissue and follow-up survey. The results showed that the positive staining rate and PU (positive unit) were obviously higher in astrocytoma than that in normal brain (86.92% vs 16.00%, P < 0.05), that the value of the positive staining rate and PU in astrocytoma corresponded closely with its pathological grade and stage (P < 0.01), and that the survival rates (6, 12, 24 months) for the patients suffering from astrocytoma gradually decreased when the VEGF positive rate increased. These suggest that the expression of VEGF may have close relationship with brain astrocytoma and the measurement of the VEGF expression may provide another potential standard for judgement about pathological grade/stage and clinical prognosis in brain astrocytoma.

Adult↗
PubMed1998

Sequence dependence and characteristics of bends induced by site-specific polynuclear aromatic carcinogen-deoxyguanosine lesions in oligonucleotides.

The tumorigenic metabolite of benzo[a]pyrene, the (+)-7R,8S,9S,10R enantiomer, and the nontumorigenic mirror-image isomer, (-)-7S,8R,9R, 10S, of r7,t8-dihydroxy-t9,10-epoxy-7,8,9, 10-tetrahydrobenzo[a]pyrene (anti-BPDE) bind covalently to the exocyclic amino group of deoxyguanosine (N2-dG) in native DNA. These adducts can cause structural perturbations such as DNA bends, which in turn may influence the cellular processing of these lesions. The characteristics of bends in site-specifically modified oligodeoxyribonucleotide duplexes induced by single (+)- and (-)-anti-[BP]-N2-dG lesions were examined by self-ligation and gel electrophoresis techniques. The modified residues (dG*) were centrally positioned in the 11-mer oligonucleotide d(CACAXG*XACAC) complexed with the natural complementary strands, with X = T or C, or in oligonucleotides 16 or 22 base pairs long with the same centrally positioned 11-mer. Among the four stereochemically distinct lesions, the 10S(+)-trans-anti-[BP]-N2-dG adducts were significantly more bent than any of the other three stereoisomeric adducts and were selected for detailed studies. In the TG*T sequence context (X = T), the retardation factor RL (apparent length of multimer/sequence length) is approximately independent of the phasing (distance, in base pairs, between the lesions) of the adducts with respect to the helical repeat (10.5 base pairs/helix turn). In contrast, in the CG*C sequence context (X = C), RL is markedly lower in the case of ligated 16-mers than in the case of ligated 11-mer duplexes. The dependence of RL on the phasing of the bends as a function of the helical repeat, indicate that the bends associated with (+)-trans-anti-[BP]-N2-dG lesions are relatively rigid in the d(...CG*C...).d(...GCG...) sequences, and flexible in the d(...TG*T...).d(...ACA...) sequence context. These differences are attributed to the orientations of the pyrenyl residues on the 5'-side of the modified deoxyguanosine residues in the minor groove and to the intrinsic roll and tilt characteristics of DNA dinucleotide steps CG, GC, TG, and GT. The influence of flanking bases on the extent and character of DNA bending suggest that base sequence effects may be important in the cellular processing of (+)-trans-anti-[BP]-N2-dG lesions.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed1998

Bending and circularization of site-specific and stereoisomeric carcinogen-DNA adducts.

The potent tumorigen and mutagen (+)-7(R),8(S)-dihydroxy-9(S), 10(R)-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene ((+)-anti-BPDE) is a metabolite of benzo[a]pyrene that binds predominantly to the exocyclic amino group of guanine residues in DNA in vivo and in vitro. While the (-)-7S,8R,9R,10Senantiomer, (-)-anti-BPDE, also reacts with DNA to form similar covalent N2-deoxyguanosyl adducts, this diol epoxide is nontumorigenic and its mutagenic activities are different from those of (+)-anti-BPDE. In this work, T4 ligase-induced cyclization methods have been employed to demonstrate that the (+)-anti-[BP]-N2-dG lesions (G*) cause significantly greater amounts of bending and circularization of the one-base overhang undecamer duplex 5'-d(CACAT[G*]TACAC).d(TGTACATGTGG) than the stereoisomeric oligonucleotide duplex with G* = (-)-anti-[BP]-N2-dG. In the case of the (+)-anti-BPDE-modified oligonucleotides, the ratio of circular to linear DNA multimers reaches values of 8-9 for circle contour sizes of 99-121 base pairs, while for the (-)-anti-[BP]-N2-dG-modified DNA this ratio reaches a maximum value of only approximately 1 at 154-176 base pairs. Assuming a planar circle DNA model, the inferred bending angles for 90-92% of the observed circular ligation products range from 30 to 51 degrees per (+)-trans-anti-[BP]-N2-dG lesion and from 20 to 40 degrees per (-)-trans-anti-[BP]-N2-dG lesion. In the case of unmodified DNA, the probability of circular product formation is at least 1 order of magnitude less efficient than in the BPDE-modified sequences and about 90% of the circular products exhibit bending angles in the range of 14 -19 degrees . In the most abundant circular products observed experimentally, the bending angles are 40 degrees and 26 +/- 2 degrees per (+)-anti-[BP]- or (-)-anti-[BP]-modified 11-mer; these values correspond to a net contribution of 21-26 degrees and 5-19 degrees , respectively, to the observed overall bending per lesion. The coexistence of circular DNA molecules of different sizes and, therefore, different average bending angles per lesion, suggest that the lesions induce both torsional flexibility and flexible bends, which permit efficient cyclization, especially in the case of (+)-trans-[BP]-N2-dG adducts. The NMR characteristics of (+)-trans-[BP]-N2-dG lesion in the 11-mer duplex 5'-d(CACAT[G*]TACAC).d(GTGTACATGTG) indicate that all base pairs are intact, except at the underlined base pairs. This suggests a distortion in the normal conformation of the duplex on the 5'-side of the modified guanosine residue, which may be due to bending enhanced base pair opening and bending induced by the bulky carcinogen residue. The implications of base sequence-dependent flexibilities and conformational mobilities of anti-[BP]-N2-dG lesions on DNA replication and mutation are discussed.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed1998

Solution structure of the aminofluorene [AF]-intercalated conformer of the syn-[AF]-C8-dG adduct opposite dC in a DNA duplex.

We report below on a conformational equilibrium between AF-intercalated and AF-external states in slow exchange for the [AF]dG lesion positioned opposite dC in the d(C-[AF]G-C).d(G-C-G) sequence context. The slow exchange between states is attributed to interconversion between syn glycosidic torsion angle in the AF-intercalated and anti torsion angle in AF-external conformers of the [AF]dG opposite dC containing duplex. The present paper describes an NMR-molecular mechanics study that defines the solution structure of the AF-intercalated conformer for the case of [AF]dG adduct positioned opposite dC in the d(C-[AF]G-C).d(G-C-G) sequence context. The structure is of the base displacement-intercalation type where the aminofluorene ring is intercalated into the helix between intact Watson-Crick dG.dC base pairs, which results in a displacement of the modified guanine ring into the major groove where it stacks with the major groove edge of its 5'-flanking cytosine in the adduct duplex. The conformational equilibrium between AF-intercalated conformer (approximately 70%) with a syn alignment and AF-external conformer (approximately 30%) with an anti alignment for the [AF]dG adduct positioned opposite dC in the d(C-[AF]G-C).d(G-C-G) sequence context can be contrasted with our earlier demonstration that the population is 100% for the AP-intercalated conformer with a synalignment at the N-(deoxyguanosin-8-yl)-2-aminopyrene ([AP]dG) adduct site positioned opposite dC in the same sequence context [Mao, B., Vyas, R. R., Hingerty, B. E., Broyde, S., Basu, A. K., and Patel, D. J. (1996) Biochemistry, 35, 12659-12670]. This shift in population may reflect the much larger size of the pyrenyl ring of the [AP]dG adduct compared to the fluorenyl ring of the [AF]dG adduct which in turn might provide for a greater overlap of the aromatic amine with the flanking base pairs in the intercalated conformer of the former adduct in DNA.

Carbon↗
PubMed1998

Solution structure of the aminofluorene [AF]-external conformer of the anti-[AF]-C8-dG adduct opposite dC in a DNA duplex.

The Escherichia coli genome contains a C-G1-G2-C-G3-C-C NarI hot spot sequence for -2 deletion mutations at G3 by aromatic amine carcinogens 2-acetylaminofluorene (AAF) and 2-aminofluorene (AF) that form covalent adducts at the C8-position of the guanine ring. Each of the three guanines are positioned in different sequence contexts (C-G1-G, G-G2-C, and C-G3-C) which provides an opportunity to investigate the potential sequence dependent interconversion between AF-intercalated and AF-external conformers of the [AF]dG adduct positioned opposite dC within the NarI sequence at the duplex level. We have prepared and purified DNA duplexes containing the [AF]dG adduct positioned in C-[AF]G-G, G-[AF]G-C, and C-[AF]G-C NarI sequence contexts and observe the ratio of AF-intercalated to AF-external conformers to be 30:70, 10:90, and 50:50, respectively. We have applied a combined NMR-molecular mechanics approach to define the structure of the AF-external conformer in the G-[AF]G-C NarI sequence context where it is the predominant conformation (90%) in solution. The modified guanine of the [AF]dG adduct aligns through Watson-Crick pairing with its partner cytosine and is stacked into the helix between flanking Watson-Crick dG.dC base pairs. The AF-external conformer with its anti-[AF]dG residue causes minimal perturbations in the DNA duplex at and adjacent to the lesion site with the covalently linked fluorenyl ring readily accommodated in the major groove and tilted toward the 5'-end of the modified strand of the helix. This paper on the structure of the AF-external conformer with an anti-[AF]dG adduct together with the preceding paper in this issue on the structure of the AF-intercalated conformer with a syn-[AF]dG adduct defines for the first time the capacity of the mutagenic [AF]dG lesion to adopt interconverting syn and antialignments with the equilibrium shifting between the conformers depending on nearest neighbor and next-nearest neighbor sequences. Perhaps, recognition of the [AF]dG lesion by the repair machinery would be able to discriminate between the AF-intercalated conformer with its base displacement-fluorenyl ring insertion perturbation of the helix and the AF-external conformer where the DNA helix is essentially unperturbed at the lesion site and the fluorenyl ring is positioned with directionality in the major groove.

Carbon↗
PubMed1998

Solution structures of stromelysin complexed to thiadiazole inhibitors.

Unregulated or overexpressed matrix metalloproteinases (MMPs), including stromelysin, collagenase, and gelatinase. have been implicated in several pathological conditions including arthritis and cancer. Small-molecule MMP inhibitors may have therapeutic value in the treatment of these diseases. In this regard, the solution structures of two stromelysin/ inhibitor complexes have been investigated using 1H, 13C, and 15N NMR spectroscopy. Both-inhibitors are members of a novel class of matrix metalloproteinase inhibitor that contain a thiadiazole group and that interact with stromelysin in a manner distinct from other classes of inhibitors. The inhibitors coordinate the catalytic zinc atom through their exocyclic sulfur atom, with the remainder of the ligand extending into the S1-S3 side of the active site. The binding of inhibitor containing a protonated or fluorinated aromatic ring was investigated using 1H and 19F NMR spectroscopy. The fluorinated ring was found to have a reduced ring-flip rate compared to the protonated version. A strong, coplanar interaction between the fluorinated ring of the inhibitor and the aromatic ring of Tyr155 is proposed to account for the reduced ring-flip rate and for the increase in binding affinity observed for the fluorinated inhibitor compared to the protonated inhibitor. Binding interactions observed for the thiadiazole class of ligands have implications for the design of matrix metalloproteinase inhibitors.

Binding Sites↗
PubMed1998

[Influence of intraspinal implantation of pSVP0MCAT genetically modified Schwann cell in regeneration of injured spinal cord].

In order to observe the role of genetically modified Schwann cell (SC) with pSVP0Mcat in the regeneration of injured spinal cord, the cells were implanted into the spinal cord. Ninety SD rats were used to establish a model of hemi-transection of spinal cord at the level of T8, and were divided into three groups, randomly, that is, pSVP0Mcat modified SC implantation (Group A), SC implantation (Group B) and without cell implantation as control (Group C). After three months the presence of axonal regeneration of the injured spinal cord was examined by means of horseradish peroxidase (HRP) retrograde labelling technique and stereography. The results indicated that HRP labelled cells in Group A and B could be found in the superior region of injured spinal cord and the brain stem such as the red nuclei and oculomotor nuclei. The density of ventral hom neurons of the spinal cord and the number of myelinated axons in 100 microns of the white matter was A > B > C group. In brief, the pSVP0Mcat modified SC intraspinal implantation could promote regeneration of the injured spinal cord.

Animals↗
PubMed1998

[[symbol: see text]-shaped splitting of spinous process for lumbar spinostenosis].

In order to modify the plastic operation for lumbar spinostenosis, [symbol: see text]-shaped splitting of spinous process was designed. Fifty-six patients with lumbar spinostenosis were treated. There were 36 males and 16 females, age ranged from 32-67 years old (with an average of 48.9 years old). Among them, 8 patients operation on L2-L5 segments, 16 on L3-L5 segments and 22 patients on L4-L5 segments. After operation, 32 cases were followed up from 8 to 27 months. The results were: 1. The result of operation was excellent in 21 cases, good in 8 fair in 2 and poor in 1. The effective rate was 90.6%. 2. The rate of bony union from laminectomy was 95.1%. 3. The sagittal diameter and transverse diameter of the spinal canal were enlarged in an average of 6.4 mm and 3.2 mm, respectively, with a mean enlargement of 37.6%. The conclusion were that the plastic operation with [symbol: see text]-shaped splitting of spinous process for lumbar spinal canal was easy to handle and it could effectively prevent the lumbar instability and secondary stenosis following operation.

Adult↗
PubMed1998

[Research status and prospects of gene therapy in spinal cord injuries].

Gene therapy develops very rapidly during the resent years. Great prospects have been demonstrated from basic study and clinic test. However, the gene therapy in CNS is still in stage of laboratory. The research status and prospects of gene therapy in spinal cord injury (SCI) were introduced. The basic principle is to transplant certain cells genetically modified with NTFs to the site of the injuried spinal cord, then NTFs are expressed in vivo and stimulate axon regrowing. Virus vectors are usually used for gene transfer because of their high rate of transfection, and the receptor cells include fibroblast, myoblast, etc. Nowadays, gene therapy in SCI is studied in many laboratories and the problems include: 1. The ideal components of transfer gene. 2. The choice of carrier. 3. Immune reaction, and prolonged survival and persistent expression of the receptor cells in the spinal cord. If these problems could be solved, the gene therapy would become the key method in the therapy of SCI.

Animals↗
PubMed1998

[The distribution of substance P in the lungs of asthmatic guinea-pigs and the influence of dexamethasone on the distribution].

OBJECTIVE: To investigate the distribution of substance P(SP) in the lungs of asthmatic guinea pigs and the effects of dexamethasone on its distribution. METHODS: Guinea pigs were divided into 3 groups: asthma group, dexamethasone-treated group and control group. Rabbit serum against SP, immunohistochemical ABC method and glucose-DAB-nickel technique for staining and computer image analysis were used in this study. RESULTS: There was distribution of SP-IR positive fibres in airways in asthma group than the other two groups. The positive fibres, emerged like a string of beads, were present as large fibre bundles in the smooth muscle layer and basement membrane. Additionally, in the asthma group SP-IR positive fibres were detected on the walls of respiratory bronchioles and alveolar ducts in contrast to the other groups. There was no difference in distribution and morphological characteristic between the control group and the dexamethasone-treated group. CONCLUSION: Repeated antigen challenges, which cause the allergic inflammation of airways, may result in the growth of SP-containing nerve fibres in the airway and synthesis of SP in neurons. These may be involved in the persistence and exacerbation of airway inflammation in asthma. Dexamethasone can reverse the distribution of SP-IR positive fibres to the normal status in airway walls of asthma guinea pigs.

Animals↗
PubMed1998

[Change of hymodynamics and circulating endothelial cells in chronic obstructive pulmonary diseases (COPD) and cor pulmonale patients].

OBJECTIVE: To investigate the vascular endothelial injuries by observing the changes of circulating endothelial cells (CEC) numbers in blood and hemodynamics in COPD and cor pulmonale patients. METHOD: The arterial catheterion technique and CEC collection technique were used, superoxide dismutase (SOD) and malondialdyhyde(MDA) levels were determined respectively. RESULT: mPAP (3.76 +/- 0.75 kPa) and CEC (16.70 +/- 2.65/0.9 microliter), MDA (6.98 +/- 1.47 mumol/L) in the chronic cor pulmonale are higher than that of mPAP (2.09 +/- 0.41 kPa) and CEC (8.48 +/- 2.23 microliters) in COPD, the numbers of CEC are adversely correlated to PaO2 (gamma = 0.9423, P < 0.001) and positively correlated with mPAP (gamma = 0.8270, P < 0.001), superoxide dismutase(SOD) was decreased. CONCLUSION: mPAP, CEC are higher in cor pulmonale than that in COPD, CEC numbers rise when the PaO2 was lowered, hypoxia may worsen the vascular endothelial injuries.

Adult↗
PubMed1998

[Gliosis: follow-up and pathological study of 34 cases].

OBJECTIVE: To discuss the etiology, clinical characteristics, pathology and canceration in gliosis. METHOD: 34 cases of gliosis were analyzed retrospectively follow-up for a long period. Their pathologic slices were restudied. RESULT: The causes of gliosis included cranial infection, specially infection caused by virus without distinct symptoms cerebral ischemia, brain injury, radiological treatment of brain. most cases showed symptoms of intracranial hypertension, 55.9% of the patients accompanied with epilepsy. Pathological examination revealed proliferation of small gliosis in all cases, lligodendrogliosis in 79.4% of the cases. The cases with proliferation had better rehabilitation. Canceration was noted in 11.8% of all cases. CONCLUSION: Gliosis is a nonmalignant disease, however, it has the possibility of canceration.

Adolescent↗