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Biomedical subjects

W Luo

Publications and source records attributed to W Luo.

At least 37 records · Page 2Linked to original sources
PubMed2001

Cardiac ischemic preconditioning improves lung preservation in valve replacement operations.

BACKGROUND: Previous work has shown that cardiac ischemic preconditioning reduces cardiac reperfusion injury. We investigated whether cardiac ischemic preconditioning can improve lung preservation in patients who undergo valve replacement. METHODS: Forty patients with rheumatic heart disease requiring valve replacement were randomly divided into two groups. Twenty patients received two cycles of 3 minutes of aortic cross-clamping and 2 minutes of reperfusion before cardioplegic arrest (group IP), and 20 patients underwent 10 minutes of cardiopulmonary bypass (group C, control group). Blood samples from the pulmonary vein were collected to measure levels of polymorphonuclear leukocytes, superoxide dismutase, malonedialdehyde, and thromboxane B2, and arterial oxygen tension. Blood samples from the coronary sinus were used to measure calcitonin gene-related peptide values. Hemodynamic data were recorded by a pulmonary artery Swan-Ganz catheter. Lung tissue was collected after 1 hour of reperfusion to evaluate morphology. Clinical outcome data were recorded. RESULTS: In group C (cardiopulmonary bypass and cardioplegic arrest), the levels of polymorphonuclear leukocytes, thromboxane B2, malonedialdehyde, and calcitonin gene-related peptide were increased after 1 hour of reperfusion, whereas the value for superoxide dismutase was decreased. In group IP, preconditioning attenuated the increase in polymorphonuclear leukocytes, thromboxane B2, and malonedialdehyde (p < 0.05) and increased superoxide dismutase and calcitonin gene-related peptide levels (p < 0.05). Preconditioning also increased arterial oxygen tension and cardiac index compared with controls (p < 0.05) and decreased mean pulmonary artery pressure and pulmonary vascular resistance index (p < 0.05). Histologic findings showed less lung injury and a lower polymorphonuclear leukocyte count in group IP than in group C (p < 0.05). Group IP had fewer postoperative pulmonary complications and a shorter intubation time. CONCLUSIONS: Cardiac ischemic preconditioning improves lung preservation in patients having valve replacement. The mechanism may be that cardiac ischemic preconditioning reduces the accumulation of polymorphonuclear leukocytes in lung tissue and decreases the formation of oxygen free radicals.

Adult↗
PubMed2001

Ministernotomy versus full sternotomy in congenital heart defects: a prospective randomized study.

BACKGROUND: Although the ministernotomy is extensively used in the repair of congenital heart defects all over the world, whether this approach has additional advantages over the conventional full sternotomy is not well established. This prospective study was designed to evaluate the effects of lower ministernotomy in the repair of congenital heart defects. METHODS: One hundred patients who underwent repair of atrial or ventricular septal defects were randomly divided into two groups: lower ministernotomy group (n = 50), and full sternotomy group (n = 50). The clinical indexes of each procedure were recorded and analyzed. RESULTS: The age, sex, and types of cardiac defects were comparable between the two groups. Ischemic times, bypass times, intensive care unit stay, and ventilation duration were similar in both groups. The procedure time (from skin to skin) was longer in the lower ministernotomy group than in the full sternotomy group (p < 0.001). There was less drainage in the lower ministernotomy group than in the full sternotomy group for the first 24 hours after operation (186 +/- 99 mL/m2 versus 237 +/- 134 mL/m2, p = 0.03) but no significant difference in transfusions between the two groups. The hospital stay was shorter in the lower ministernotomy group than in the full sternotomy group (6.5 +/- 1.2 days versus 7.5 +/- 1.8 days, p = 0.02). CONCLUSIONS: Ministernotomy is as safe and effective as a full sternotomy in the repair of simple congenital heart defects in older children and adults. Furthermore, this small incision reduces the postoperative drainage, shortens hospital stay, and provides better cosmetic results. Operative times are longer.

Adolescent↗
PubMed2001

Regulated gene expression dictates enamel structure and tooth function.

Enamel is a complex bioceramic tissue. In its final form, enamel is a reflection of the unique molecular and cellular activities occurring during organogenesis. From the ectodermal origins of ameloblasts, their gene activity and protein expression profiles exist for the sole purpose of producing a mineralized shell, almost entirely devoid of protein, deposited over the 'bone-like' dentine. The interface between enamel and dentine is referred to as the dentine enamel junction and it is also unique in its biology. This review article is narrow in its scope. We restrict our review to selected advances in our understanding of the genetic, molecular and structural aspects of enamel biology. We present a model of enamel formation that relates gene expression to the assembly of an extracellular protein matrix that in turn controls the structural hierarchy and mechanical aspects of enamel and the tooth organ.

Amelogenin↗
PubMed2001

Characterization of hydantoin products from one-electron oxidation of 8-oxo-7,8-dihydroguanosine in a nucleoside model.

Use of one-electron oxidants such as Na(2)IrCl(6) to oxidize 8-oxo-7,8-dihydro-2'-deoxyguanosine (OG) residues in oligodeoxynucleotides was previously shown to lead to predominant formation of a base lesion of mass M - 10 compared to starting material [Duarte et al. (1999) Nucleic Acids Res. 27, 596-502]. To thoroughly characterize the structure of this lesion, the oxidation of the nucleoside 9-N-(2',3',5'-tri-O-acetyl-beta-D-erythro-pentanosyl)-8-oxo-7,8-dihydroguanine with one-electron oxidants at pH 2-4 was used as a model for duplex DNA oxidation of OG residues. (1)H NMR and H,H COSY NMR studies in CD(3)OD along with LC-ESI-MS/MS fragmentation analysis are consistent with the assignment of the M - 10 species as a mixture of two pH-dependent equilibrating isomers, a guanidinohydantoin (Gh) and an iminoallantoin (Ia) nucleoside, both present as mixtures of epimers at the C5 position of the hydantoin ring, i.e., four total isomers are formed. The Gh/Ia mixture is formed from hydration and decarboxylation of the initially formed intermediate 5-hydroxy-8-oxo-7,8-dihydroguanosine, a species that is also produced by four-electron oxidation (e.g., singlet oxygen) of guanosine. The product mixture can be further oxidized to a species designated Ia(ox), a hydrolytically unstable material at pH 7 that has been characterized by ESI-MS and (1)H NMR. Competition studies with 8-oxo-7,8-dihydroadenosine placed the redox potential of Gh/Ia at about 1.0 V vs NHE. These studies provide important information concerning the structures of lesions obtained when OG, a "hot spot" for oxidative damage, serves as a "hole trap" in long-range electron-transfer studies.

Allantoin↗
PubMed2001

Cardiac chamber-specific alterations of ANP and BNP expression with advancing age and with systemic hypertension.

The present study determined cardiac chamber-specific alterations of the expression of the atrial and brain natriuretic peptide (ANP and BNP) genes with a small increase in age beyond adulthood and with systemic hypertension of intermediate duration. The expression distributions of these genes was determined using in situ hybridization in the right and left atria (RA and LA), and the right and left ventricles (RV and LV) in Wistar Kyoto rats (WKY) and age-matched Spontaneously Hypertensive rats (SHR) at ages 6 months (adult) and 8 months (advanced-age beyond adulthood). In all rat groups, both genes were expressed (ANP > BNP) in the LA and LV, and were not expressed in the RA and RV. The genes were expressed in the LA in all rat groups; the ANP, but not the BNP, expression increased with advancing age and with superimposed hypertension. They were expressed in the LV of the advanced-age WKY, adult and advanced-age SHR, but not in the adult WKY. The ANP mRNA labeling in the LA was diffuse and interspersed with dense accumulations, whereas BNP labeling was diffuse. The labeling of both genes in the form of sparse clusters was seen in the LV of the advanced-age SHR. Our study showed that ANP and BNP expression in left heart chambers increased with a small increase in age, with hypertension of intermediate duration, and with modest left ventricular hypertrophy. The chamber-specific expression distribution could be due to special groups of cardiac cells, or to local chamber-specific factors.

Age Factors↗
PubMed2001

Intrahousehold food distribution: a case study of eight provinces in China.

A longitudinal survey of health and nutrition in China was undertaken in eight provinces (Liaoning, Jiangsu, Shandong, Henan, Hubei, Hunan, Guangxi, Guizhou). Data were collected in 1989, 1991, 1993 and 1997. The 1991 and 1993 data were used to investigate factors affecting intrahousehold food distribution. The discrepancy score and the ratio of food share to energy share were used to describe food distribution within households. Findings indicated that, in most cases, males had a higher proportion of nutrient intake than females, particularly in the young adult group where men presented with a higher discrepancy score than women for energy and all nutrients observed. The food and nutrient distribution tends to be more favourable to the middle-aged group, although the youngest group, while accepting relatively smaller amounts of cereals, ate much bigger amounts of meat, dairy products and fruits. Household members with higher incomes are more favoured in terms of food consumption and nutrient intake. Household leaders accepted a higher share of energy and nutrients in comparison with other members of the household across all age and sex groups. Administrators and people working in service or trade industries in rural areas are favoured in terms of food distribution relative to farmers and manual workers. Well-educated people accepted a better food allocation than others and those in employment received more nutrients than the unemployed. The 'contribution rule' (individuals who make a greater contribution to the family receive a larger share of the family's food) is discussed and deemed to be applicable in explaining the discrepancy in food distribution and nutrient intake among household members.

Adolescent↗
PubMed2001

Chaperone-like activity of peptidyl-prolyl cis-trans isomerase during creatine kinase refolding.

Porcine kidney 18 kD peptidyl-prolyl cis-trans isomerase (PPIase) belongs to the cyclophilin family that is inhibited by the immunosuppressive drug cyclosporin A. The chaperone activity of PPIase was studied using inactive, active, and alkylated PPIase during rabbit muscle creatine kinase (CK) refolding. The results showed that low concentration inactive or active PPIase was able to improve the refolding yields, while high concentration PPIase decreased the CK reactivation yields. Aggregation was inhibited by inactive or active PPIase, and completely suppressed at 32 or 80 times the CK concentration (2.7 microM). However, alkylated PPIase was not able to prevent CK aggregation. In addition, the ability of inactive PPIase to affect CK reactivation and prevent CK aggregation was weaker than that of active PPIase. These results indicate that PPIase interacted with the early folding intermediates of CK, thus preventing their aggregation in a concentration-dependent manner. PPIase exhibited chaperone-like activity during CK refolding. The results also suggest that the isomerase activity of PPIase was independent of the chaperone activity, and that the proper molar ratio was important for the chaperone activity of PPIase. The cysteine residues of PPIase may be a peptide binding site, and may be an essential group for the chaperone function.

Creatine Kinase↗
PubMed2001

G protein coupling to M1 and M3 muscarinic receptors in sublingual glands.

Rat sublingual gland M2 and M3 muscarinic receptors each directly activate exocrine secretion. To investigate the functional role of coreceptor expression, we determined receptor-G protein coupling. Although membrane proteins of 40 and 41 kDa are ADP-ribosylated by pertussis toxin (PTX), and 44 kDa proteins by cholera toxin (CTX), both carbachol-stimulated high-affinity GTPase activity and the GTP-induced shift in agonist binding are insensitive to CTX or PTX. Carbachol enhances photoaffinity labeling ([alpha-(32)P]GTP-azidoaniline) of only 42-kDa proteins that are subsequently tractable to immunoprecipitation by antibodies specific for Galpha(q) or Galpha(11) but not Galpha(12) or Galpha(13). Carbachol-stimulated photoaffinity labeling as well as phosphatidylinositol 4,5-bisphosphate (PIP2) hydrolysis is reduced 55% and 60%, respectively, by M1 receptor blockade with m1-toxin. Galpha(q/11)-specific antibody blocks carbachol-stimulated PIP2 hydrolysis. We also provide estimates of the molar ratios of receptors to Galpha(q) and Galpha(11). Although simultaneous activation of M1 and M3 receptors is required for a maximal response, both receptor subtypes are coupled to Galpha(q) and Galpha(11) to stimulate exocrine secretion via redundant mechanisms.

Affinity Labels↗
PubMed2001

Biological organization of hydroxyapatite crystallites into a fibrous continuum toughens and controls anisotropy in human enamel.

Enamel forms the outer surface of teeth, which are of complex shape and are loaded in a multitude of ways during function. Enamel has previously been assumed to be formed from discrete rods and to be markedly aniostropic, but marked anisotropy might be expected to lead to frequent fracture. Since frequent fracture is not observed, we measured enamel organization using histology, imaging, and fracture mechanics modalities, and compared enamel with crystalline hydroxyapatite (Hap), its major component. Enamel was approximately three times tougher than geologic Hap, demonstrating the critical importance of biological manufacturing. Only modest levels of enamel anisotropy were discerned; rather, our measurements suggest that enamel is a composite ceramic with the crystallites oriented in a complex three-dimensional continuum. Geologic apatite crystals are much harder than enamel, suggesting that inclusion of biological contaminants, such as protein, influences the properties of enamel. Based on our findings, we propose a new structural model.

Anisotropy↗
PubMed2001

[X-linked recessive Charcot-Marie-Tooth disease and Cx32 gene mutation].

OBJECTIVE: To study the Cx32 gene mutation in a X-linked recessive Charcot-Marie-Tooth disease (CMTXR) family. METHODS: Mutation analysis of Cx32 was screened by polymerase chain reaction single strand conformation polymorphism (PCR-SSCP) combined with DNA direct sequencing in 4 patients, 9 unaffected family members and 50 unrelated normal individuals. RESULTS: Arg15Gln mutation was found in 4 patients and 3 unaffected family members. CONCLUSION: The mutation of Cx32 can also cause CMTXR. Using PCR-SSCP combined with DNA direct sequencing can make gene diagnosis to CMTXR that is caused by Cx32 mutation.

Adult↗
PubMed2001

[Antigen receptor V beta gene usage of T lymphocytes in diseased thyroids in patients with autoimmune thyroid diseases].

OBJECTIVE: To explore the patterns of TCR V beta gene families and the preferentially used V beta genes in intrathyroidal T lymphocytes (ITL) of patients with Graves disease and Hashimoto thyroiditis. METHODS: Thyroid tissues of 12 patients with Graves disease, and 15 patients with Hashimotos thyroiditis were used for RNA extraction. Then, the RNA was used as templates for RT-PCR with a panel of primers including 24 oligonucleotides specific for TCR V beta gene families as upstream primers and one oligonucleotide specific for C beta as downstream primer. The amplified products were subjected to electrophoresis in agarose gels and observed under UV light. The positive expression of TCR V beta gene was identified by comparing the products with the size of the designed V beta genes. The matched peripheral blood samples of 5 Graves patients, 5 Hashimoto thyroiditis patients and 7 normal subjects were also obtained and used as controls. RESULTS: In 24 TCR V beta gene families tested for each individual sample, their average expressions were 5.3 +/- 1.2 and 13.4 +/- 3.0 in thyroid specimens of patients with Graves disease and Hashimoto thyroiditis, respectively, while those in the matched peripheral blood lymphocytes of the above two groups and normal controls were 23.0 +/- 1.0, 22.2 +/- 1.3 and 22.4 +/- 1.7, respectively. In addition, some of the TCR V beta genes such as V beta 3, V beta 5 and V beta 8 were more frequently used by intrathyroidal lymphocytes of Graves disease. CONCLUSIONS: These data indicate the oligoclonality of the intrathyroidal T cell populations in patients with Graves disease. Also, those of the preferentially used TCR V beta genes can be regarded as molecular targets for specific immune intervention. In contrast, the loss of restriction of TCR V beta gene utilization exists in Hashimoto thyroiditis, which may be related to the recruitment of T lymphocytes in thyroid glands through this mechanism.

Adult↗
PubMed2001

[Inhibitory effects of beta-carotene on hepatic cancer cell line SMMC-7721].

The inhibitory effect of beta-carotene on the proliferation of hepatic cancer was studied. Cells from a hepatic cancer cell line SMMC-7721 were incubated in culture media with 20, 40 and 80 mumol/L beta-carotene for 12, 24 and 48 h respectively. MTT test, Trypan blue exclusion test and DNA gel electrophoresis were used. The results of MTT test revealed that beta-carotene (20-80 mumol/L) could inhibit the proliferation of SMMC-7721 cells in a dose-dependent manner. DNA gel electrophoresis showed that the apoptosis of hepatic cancer cells could be induced by beta-carotene (40 mumol/L). It is concluded that the proliferation of hepatic cancer cells inhibited by beta-carotene, probably through interfering DNA metabolism and inducing cell apoptosis.

Antineoplastic Agents, Phytogenic↗
PubMed2001

[The research and development of computer workstation for Bayer Clinitek urine analyzer].

Computerization and networking is the developing trend of modern medical instruments. This paper describes the research and development work of computer workstation for Bayer Clinitek urine analyzer, including the system designing, hardware composing and software programming. The system can receive analyzing data automatically, manage sample database, print sample report and share data via the network, etc.

Computer Communication Networks↗
PubMed2001

[Preliminary study of the facial nerve regeneration in the chamber: the influence of myelin basic protein].

OBJECTIVE: To study the role of exogenous myelin basic protein(MBP) in neural repairment. METHODS: Adult New Zealand rabbits were employed in vivo preparation. A 12 microL nerve growth chamber was created by suturing the proximal and distal stumps of a transected facial never (FN) trunk into a tube. The regenerated nerves within the chambers were dissected and fixed for histological studies with light microscope at 4, 6 and 8 weeks respectively following the surgery. RESULTS: Morphological analysis of nerves showed no difference between the MBP and control group in the size of the regeneration FN within the chambers, diameters of myelinated axons, thickness of myelin sheath and number of myelin axons grew into the distal end of chamber at 4 weeks. At 6 and 8 weeks after operation, the MBP group showed a more mature-appearance regenerative nerve comparing to control group. Especially, the enhancement of maturation in the regeneration axons was very noticeable at 6 weeks. CONCLUSION: The study showed that pharmacological administration of exogenous MBP within a chamber at the time of entubational nerve repair enhances regeneration of myelinated axons across the sectioned ends of FN.

Animals↗