PubMed Health⌕ Search

Biomedical subjects

B Gu

Publications and source records attributed to B Gu.

72 records · Page 4Linked to original sources
PubMed1990

Repair of a huge defect of the gluteal region by rotation of a combined tensor fasciae latae-sartorius myocutaneous flap.

Although the tensor fasciae latae myocutaneous flap is convenient for covering some defects in the gluteal region, it is not suitable to repair a huge defect because of its limited area. Based on the close relationship of the sartorius and the tensor fasciae latae at their origins and blood supply, the authors designed a myocutaneous flap containing both the tensor fasciae latae and the sartorius muscles and their skin territories with an area exceeding 800 cm2. Two successfully repaired patients are reported. The flaps provide normal sensitivity. The vascular pedicle has a reliable anatomy, being easily dissected, and averages 4.6 to 5.8 cm in length. Both muscles are expendable. There is little functional difficulty for hip joint after the operation.

Aged↗
PubMed1990

Rhizobium meliloti and Rhizobium leguminosarum dctD gene products bind to tandem sites in an activation sequence located upstream of sigma 54-dependent dctA promoters.

Free-living rhizobia transport external C4-dicarboxylates to use as sole carbon sources, and uptake of these compounds is essential for nitrogen fixation by rhizobial bacteroids. In both Rhizobium leguminosarum and Rhizobium meliloti, the genes dctB and dctD are believed to form an ntrB/ntrC-like two-component system which regulates the synthesis of a C4-dicarboxylate transport protein encoded by dctA. Here we confirm the identity of sigma 54-dependent promoters previously hypothesized for the R. leguminosarum and R. meliloti dctA genes and demonstrate that repeated, partial dyad symmetry elements located about 75 base pairs upstream of each promoter are essential for fully regulated transcription. Furthermore, we show that both repeats bound dctD protein and that together they resulted in succinate-sensitive transcription when placed upstream of another sigma 54 consensus promoter, that of R. meliloti nifH.

Base Sequence↗
PubMed1990

[Clinical use of lyophilized porcine skin].

The split-thickness lyophilized porcine skin has been proved to be an effective biologic wound dressing, which is convenient for storage, transport and usage. It can be used as a temporary skin coverage for fresh burn wound and the wound remained after escharectomy or used as mesh grafts to prevent infection and loss of body fluids so as to improve the general condition. It can also be used for covering the infective granulation wound caused by burn or injuries to control bacterial growth and further contamination. In these circumstances, the lyophilized xenografts tend to autolysis and can persist in a rather short time. It should be replaced repeatedly in order to get a surgical clean wound surface suitable for autografts. More than 100 cases with burn or injuries have been treated with the recommended method since 1979. Results showed that the lyophilized porcine skin is a good choice as a satisfactory substitute for allografts which often served as a biologic dressing.

Adolescent↗
PubMed1989

China's super-large cities: dominance and integration.

"This study is mainly intended to survey the ecological structure, particularly the dominance and integration [of economic development], of 20 super-large cities in China. Most of the statistics used in this study come from the China Statistical Yearbook (1984), according to which all the 20 cities have a population of more than two million."

Asia↗
PubMed1988

Role of glycoprotein B of herpes simplex virus type 1 in viral entry and cell fusion.

Glycoprotein B (gB) of herpes simplex virus type 1 is an envelope protein that is essential for viral growth. We previously reported the isolation of two gB-null viruses, which form gB-free virions in nonpermissive cells. In the present study, these gB-free virions were shown to bind to the cell surface at the same rate as the wild-type virus. They failed, however, to form plaques and to synthesize virus-specific proteins upon infection. Their plating efficiency was significantly enhanced by treatment with polyethylene glycol, a membrane fusion agent. Therefore, gB is required in a stage after viral attachment but before the expression of the virus-specific proteins. A gB-null syncytial virus was isolated, which contained a gB defect and a syncytial mutation in another genetic locus. It caused complete fusion of gB-transformed cells but no fusion on untransformed cells, indicating the essential role of gB in virus-induced cell fusion. Mutations located at two independent sites in the cytoplasmic domain of gB were transferred to viral DNA and shown to confer a syncytial phenotype to the virus. A transient-expression assay was developed to determine the ability of a set of plasmids containing addition and nonsense mutations in the gB gene to complement the cell-fusion defect in the gB-null syncytial virus. Mutations in plasmids, including those located in the extracytoplasmic domain of gB, were identified that reduced the fusion activity of gB. Therefore, gB contains different functional regions responsible for fusion induction and its inhibition.

Cell Fusion↗
PubMedDate not supplied

Hypoxia-induced increase in soluble Flt-1 production correlates with enhanced oxidative stress in trophoblast cells from the human placenta.

OBJECTIVE: Placental trophoblast cells (TCs) produce soluble Flt-1 (sFlt-1). Hypoxia induces placental oxidative stress and modulates trophoblast function. The aim of this study was to investigate whether hypoxia mediates TC sFlt-1 production and whether increased sFlt-1 production correlates with increased oxidative stress in placental TCs. METHODS: Placentas were obtained immediately after delivery from normal pregnant women (n = 8). Placental TCs were isolated by Dispase digestion of villous tissue and purified by Percoll gradient centrifugation. Isolated TCs were cultured under normoxia (21% O2: 5% CO2/95% air) and hypoxia (2% O2/5% CO2/93% N2) conditions for 3 days in vitro. TC productions of sFlt-1, VEGF, and PlGF were measured by enzyme-linked immunosorbent assay (ELISA). Lipid peroxide production and superoxide dismutase (CuZn-SOD) levels were evaluated. Messenger RNA expressions of Flt-1, VEGF and PlGF were determined by RT-PCR. Messenger RNA expressions for superoxide dismutase (CuZn-SOD) and heme oxygenase-1 (HO-1) were also determined. Data are expressed as mean +/- SE. A p level less than 0.05 was considered statistically different. RESULTS: Our results show that sFlt-1 production was significantly increased by TCs cultured under hypoxia condition that correlates with increased lipid peroxide production. We also found that under hypoxia condition: (1) the ratio of PlGF/VEGF production was reversed; (2) the ratio of lipid peroxides to superoxide dismutase production was increased. The increased mRNA expressions for Flt-1 and VEGF and the decreased mRNA expression for PlGF in TCs were consistent with the protein productions under hypoxia condition. CONCLUSION: We concluded that upregulation of sFlt-1 and unbalanced PlGF/VEGF production associated with increased oxidative stress are consequences of hypoxia in placental TCs. Our results suggest that placental TCs are major sources of sFlt-1 and VEGF levels in the maternal circulation in women with preeclampsia.

Cell Hypoxia↗
PubMedDate not supplied

Son preference and the sex ratio at birth in China: a provincial level analysis.

In this paper we use data from the 1 Per Cent Sample of the 1990 Census of China to calculate sex ratios for the Chinese provinces that are specific not only to parity, but also to the sex composition of previously-born children. We analyze the degree of relationship among and between the SRB's and then consider the phenomenon of son preference. We find the variation in sex ratios at birth among the Chinese provinces is related in an important way to variation among the provinces in the degree of son preference. Our analysis shows abnormally high SRB's in most of the provinces of China, especially at parities 2 and higher when the prior births were daughters. Other societies, namely Taiwan and South Korea, with rapid fertility decline and strong son preference also manifest abnormally high SRB's at parities beyond the first.

China↗
PubMedDate not supplied

Impact of sample preparation on mineralogical analysis of zero-valent iron reactive barrier materials.

Permeable reactive barriers (PRBs) of zero-valent iron (Fe(0)) are increasingly being used to remediate contaminated ground water. Corrosion of Fe(0) filings and the formation of precipitates can occur when the PRB material comes in contact with ground water and may reduce the lifespan and effectiveness of the barrier. At present, there are no routine procedures for preparing and analyzing the mineral precipitates from Fe(0) PRB material. These procedures are needed because mineralogical composition of corrosion products used to interpret the barrier processes can change with iron oxidation and sample preparation. The objectives of this study were (i) to investigate a method of preparing Fe(0) reactive barrier material for mineralogical analysis by X-ray diffraction (XRD), and (ii) to identify Fe mineral phases and rates of transformations induced by different mineralogical preparation techniques. Materials from an in situ Fe(0) PRB were collected by undisturbed coring and processed for XRD analysis after different times since sampling for three size fractions and by various drying treatments. We found that whole-sample preparation for analysis was necessary because mineral precipitates occurred within the PRB material in different size fractions of the samples. Green rusts quickly disappeared from acetone-dried samples and were not present in air-dried and oven-dried samples. Maghemite/magnetite content increased over time and in oven-dried samples, especially after heating to 105 degrees C. We conclude that care must be taken during sample preparation of Fe(0) PRB material, especially for detection of green rusts, to ensure accurate identification of minerals present within the barrier system.

Chemical Precipitation↗
PubMedDate not supplied

Mineralogical characteristics and transformations during long-term operation of a zerovalent iron reactive barrier.

Design and operation of Fe0 permeable reactive barriers (PRBs) can be improved by understanding the long-term mineralogical transformations that occur within PRBs. Changes in mineral precipitates, cementation, and corrosion of Fe0 filings within an in situ pilot-scale PRB were examined after the first 30 months of operation and compared with results of a previous study of the PRB conducted 15 months earlier using X-ray diffraction and scanning electron microscopy employing energy dispersive X-ray and backscatter electron analyses. Iron (oxy)hydroxides, aragonite, and maghemite and/or magnetite occurred throughout the cores collected 30 mo after installation. Goethite, lepidocrocite, mackinawite, aragonite, calcite, and siderite were associated with oxidized and cemented areas, while green rusts were detected in more reduced zones. Basic differences from our last detailed investigation include (i) mackinawite crystallized from amorphous FeS, (ii) aragonite transformed into calcite, (iii) akaganeite transformed to goethite and lepidocrocite, (iv) iron (oxy)hydroxides and calcium and iron carbonate minerals increased, (v) cementation was greater in the more recent study, and (vi) oxidation, corrosion, and disintegration of Fe0 filings were greater, especially in cemented areas, in the more recent study. If the degree of corrosion and cementation that was observed from 15 to 30 mo after installation continues, certain portions of the PRB (i.e., up-gradient entrance of the ground water to the Fe0 section of the PRB) may last less than five more years, thus reducing the effectiveness of the PRB to mitigate contaminants.

Calcium Carbonate↗