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Biomedical subjects

J Gu

Publications and source records attributed to J Gu.

At least 271 records · Page 15Linked to original sources
PubMed1994

Comprehensive quality management program for radiation oncology.

A quality management program for both external beam irradiation (electron and photon modes) and brachytherapy (high dose rate (HDR) and low dose rate (LDR) has been developed. The program follows current USA federal regulations for therapeutic administration of by-product materials. After implementation of the program, 54 HDR patients, 36 LDR brachytherapy patients and 311 external beam patients (including 30 stereotactic radiosurgery cases) were treated. The results of this program are presented.

Brachytherapy↗
PubMed1994

Cloning of a DNA binding protein that is a tyrosine kinase substrate and recognizes an upstream initiator-like sequence in the promoter of the preprodynorphin gene.

A 90 bp fragment prepared from the promoter region of the rat preprodynorphin gene formed a complex with rat brain nuclear extracts as assessed by gel mobility shift assays. An 8 base pair sequence, CACTCTCC, termed upstream regulatory element (URE), was identified within this fragment as a binding site by DNase 1 footprint analysis and gel mobility shift assays with synthetic oligonucleotides. The URE is a consensus sequence for a transcription initiator (Inr) element although in the preprodynorphin promoter it is located upstream at -208 and overlaps a region conserved between rat and human promoters. A unique 310 amino acid protein (UreB1) that specifically bound the URE was cloned from a rat brain cDNA library using the URE-containing oligonucleotide. Recombinantly expressed, affinity purified UreB1 protein retains specific binding to the URE oligonucleotide. UreB1 contains a tyrosine kinase phosphorylation consensus and binding is enhanced following phosphorylation with the p43v-abl tyrosine kinase. The UreB1 tyrosine phosphoprotein increases transcription in vitro, consistent with a positive transcriptional regulatory function. UreB1 transcripts are well expressed in subsets of neurons in multiple brain areas suggesting that, in addition to regulation of the preprodynorphin gene, it may have a more generalized role in gene transcription.

Amino Acid Sequence↗
PubMed1994

Efficacy of autologous peritoneum as a biological membrane in cardiac surgery.

The risks for reoperative cardiac surgery are related to the presence of intrapericardial adhesions and the possibility of catastrophic injury at repeat sternotomy. In an attempt to develop an improved pericardial substitute and vascular patch, the feasibility of using autologous peritoneum was evaluated. Twelve mongrel dogs were studied. A peritoneal-rectus fascia patch, including the overlying posterior rectus sheath was harvested, via a lateral abdominal incision, and stored in normal saline. In the first group of six animals, a pulmonary artery (PA) window was created and then closed with the peritoneal-rectus fascia patch. In the second group a secundum atrial septal defect was created and then closed with the peritoneal patch on cardiopulmonary bypass (CPB). In each animal, the peritoneal-rectus fascia patch was used to permit pericardial closure. Autopsies performed at 90 days postoperatively revealed only slight intrapericardial adhesion formation and a mild epicardial reaction. Histological examination of the peritoneal-rectus fascia patches revealed intact morphology with active fibroblasts and smooth muscle cells. Proline 14C absorption and autoradiography detected viable cells in the implanted patches. These findings suggest that a peritoneal-rectus fascia allograft could be useful as a biological membrane, and as a satisfactory pericardial substitute in the development of strategies to reduce the risk for reoperative cardiac surgery.

Animals↗
PubMed1994

Rescue of a maize mitochondrial cytochrome oxidase mutant by tissue culture.

The maize NCS6 mitochondrial mutation is a partial deletion of the cytochrome oxidase subunit 2 gene (cox2) that survives heteroplasmically in the plant. Mutant mitochondria segregate from normal mitochondria during somatic development giving rise to defective sectors on the plants, including areas of kernel abortion on the ears. Embryos from NCS6 kernels can be rescued by tissue culture. Slowly growing Type II callus derived from one of these embryos has been shown by PCR analysis to be homoplasmic for the mutation, carrying only the defective mitochondrial cox2 gene. Most of the rescued embryos were heteroplasmic for normal and mutant genes and heteroplasmy was maintained in the callus cultures. However, when suspension cultures were initiated from heteroplasmic calli, normal cells were shown to have a selective advantage. When the homoplasmic cox2 mutant callus cultures were placed on regeneration medium, plantlets did not regenerate. Heteroplasmic calli were capable of regeneration under the same conditions. These studies suggest that the functioning of mitochondrial cytochrome oxidase is not essential for growth as callus, but is required for the differentiation and development of plants.

Base Sequence↗
PubMed1994

Compilation of small RNA sequences.

This is an update containing small RNA sequences deposited in GenBank recently. Over four hundred small RNA sequences are available in this and earlier complications.

Animals↗
PubMed1994

Combined effects of magnesium deficiency and an atherogenic level of low density lipoprotein on uptake and metabolism of low density lipoprotein by cultured human endothelial cells. II. Electron microscopic data.

The effects of magnesium deficiency on low density lipoprotein (LDL) transport by cultured endothelial cells with a high concentration of LDL (2 mg of LDL cholesterol/ml) were investigated by electron microscopy and by counting the radioactivity of [3H]-LDL transported across an endothelial monolayer grown on culture plate inserts. Electron microscopic examination showed that the number of pits/vesicles in the apical side was time-dependently increased for 24 h in both magnesium-deficient and magnesium-sufficient groups with the exception of 1 h under magnesium sufficiency. The number of pits/vesicles in the basal side was also increased for 8 h in both groups, though there was a decrease at 24 h in the two groups. No difference between either magnesium group at the same time point was statistically significant. [3H]-LDL transport was also time-dependently increased in both magnesium-deficient and magnesium-sufficient groups. In contrast to the results obtained by electron microscopy, the amount of LDL transported under magnesium deficiency was much larger for 24 h than under magnesium sufficiency. Differences in LDL transport between magnesium groups were statistically significant at 4 and 8 h. This finding indicates that magnesium deficiency increases LDL transport across the endothelial monolayer. The increase may be due to energy-dependent movement across endothelial cells, energy-independent movement between cells, or both. However, we conclude that magnesium deficiency increases the energy-dependent LDL transport to some degree since intercellular gap formations were rarely observed in either magnesium group. This LDL transported to the subendothelial space may lead to LDL accumulation and initiate atherosclerosis.

Arteriosclerosis↗
PubMed1993

N-acetylglucosaminyltransferase III and V messenger RNA levels in LEC rats during hepatocarcinogenesis.

The LEC (Long-Evans with a cinnamon-like color) rat is a mutant of the Long-Evans strain which develops hereditary hepatitis and hepatoma with age. Activities and mRNA levels of N-acetylglucosaminyltransferase III and V (GnT-III and GnT-V, respectively) were determined during hepatocarcinogenesis in this rat using a LEA (Long-Evans with an agouti color) rat as a control. GnT-III activity in LEC rat liver increased after 30 weeks of age, at the stage of chronic hepatitis, to about 2.5-11.5 times the level in LEC rats aged 1-9 weeks. GnT-V activity in the LEC rat liver increased after 20 weeks of age, at the stage of acute hepatitis, to about 1.5-2.5 times the level in LEC rats of 1-9 weeks of age and then remained elevated. Both enzymes showed more dramatic increases in males than in females. The mRNA levels of the enzymes increased in proportion with the enzyme activities. Furthermore, GnT-III and GnT-V mRNAs were highly expressed in both cancer lesion and adjacent tissues. In one case of hepatoma with lymph node metastasis, GnT-III and GnT-V mRNA expression was much higher in the metastatic lesion than in the original cancer. GnT-III and GnT-V levels in the original cancer lesions were similar to those in the cancer lesions of the other LEC rats. These results indicated that expression of GnT-III and GnT-V was induced by chronic liver damage and hepatocarcinogenic changes in the LEC rats.

Age Factors↗
PubMed1993

Application of GPIIIa gene Taq I polymorphism to determination of carrier status in Glanzmann's thrombasthenia families of Chinese origin.

Glanzmann's thrombasthenia is a bleeding disorder caused by qualitative and/or quantitative defects of platelet membrane glycoprotein (GP) IIb/IIIa complex. The disease is inherited in an autosomal recessive manner. In this paper, cDNA probes were used to study restriction fragment length polymorphisms (RFLPs) in GPIIIa gene. A Taq I polymorphism was identified and this RFLP was composed of variant bands of 6.5 Kb/4.0 and 2.5 Kb with a frequency of 0.46/0.54 in Chinese population. The Taq I polymorphism was further localized by polymerase chain reaction (PCR) method to exon VIII of the GPIIIa gene. In two Glanzmann's thrombasthenia families, the Taq I RFLP studied by both Southern blotting and PCR methods identified the defective GPIIIa gene inherited by patients, and determined the genotype of asymptomatic subjects. Analysis of this Taq I polymorphism by PCR method should be potentially useful in future for the carrier detection and prenatal diagnosis in Glanzmann's thrombasthenia families.

China↗
PubMed1993

Determinants of contraceptive method choice after first delivery, before first abortion, and after first abortion in east China.

A 10% sample of the data from East China from the two-per-thousand fertility and contraception survey of the Chinese State Family Planning Committee was analysed to study determinants of contraceptive choice in three situations: after first surviving delivery; before first abortion after first surviving delivery; and after first abortion. A total of 2880 women were included. For first method choice after first delivery, the most popular method is the IUD, although there are urban/rural differences. Better educated women in urban areas prefer the condom and IUD to the pill, whereas better educated women in rural areas prefer the pill. Younger women prefer the IUD and the pill. For last method choice before first abortion, women who had no sons had apparently high failure rates on the pill.

Abortion, Induced↗
PubMed1993

Identification, localization and developmental studies of rat prepro thyrotropin-releasing hormone mRNA in the testis.

Thyrotropin-releasing hormone (TRH) plays the central regulatory role in the hypothalamic-pituitary-thyroid axis, but is also present in many extra-hypothalamic loci. The adult rat testis has been identified previously as a source of hypothalamic neuropeptides including TRH. To investigate whether the TRH gene is transcribed in testis, the identification and localization of prepro(pp) TRH mRNA and TRH were studied. Northern blot analyses of ppTRH mRNA in the adult rat testis showed a 2.0 kb band, hybridized with a ppTRH cRNA probe. This band was 0.4 kb greater than the 1.6 kb hypothalamic band. The concentration of ppTRH mRNA in the adult testis was approximately 13% of that found in the hypothalamus. Developmental studies of testicular ppTRH mRNA revealed that no ppTRH mRNA could be detected at the earliest stage (day 8). However, hybridization signals were detected on day 20 and increased progressively on days 35, 45 and 70 by 5.8, 6.4, and 9.8-fold, respectively. In addition, ppTRH mRNA was determined in Leydig cells by Northern analyses of elutriated testicular cell fractions. TRH was also measured in the rat testes at different developmental stages by RIA. TRH concentrations paralleled ppTRH mRNA during development. TRH was localized to Leydig cells by immunohistochemistry. These results indicate that ppTRH mRNA and TRH are present in the rat testis, especially in the Leydig cells. The changes of ppTRH gene expression and the concentration of TRH in the rat testis are developmentally dependent. TRH may function as a new paracrine or autocrine regulator of testicular function.

Animals↗
PubMed1993

Acquired amegakaryocytic thrombocytopenic purpura with a Philadelphia chromosome.

A 30-year-old Chinese man with acquired amegakaryocytic thrombocytopenic purpura (AATP) and a Ph chromosome is reported. At presentation, he had severe thrombocytopenia resulting in epistaxis, gingival bleeding, and ecchymoses, while other hematologic values were within the normal range. Bone marrow aspiration showed no megakaryocytes, with a normal appearance of erythroblastic and granulopoietic series. He failed to respond to prednisone treatment, and underwent a progress from isolated thrombocytopenia to full pancytopenia. At last he died of spontaneous intracranial hemorrhage. An in vitro culture for granulocyte-macrophage precursors showed very few colonies. Karyotypic analysis revealed a standard Ph chromosome translocation, t(9;22)(q34;q11), in the majority of bone marrow cells. Southern blot analysis using a 3' bcr-HE probe didn't detect a rearrangement within the bcr DNA sequence. This patient, in fact, was a myelodysplastic disorder, initially presenting as AATP. The diagnosis of chronic myelogenous leukemia was excluded on the basis of clinical and hematologic findings. The heterogeneity of Ph chromosome in myelodysplastic syndrome is discussed.

Adult↗
PubMed1993

Purification and characterization of UDP-N-acetylglucosamine: alpha-6-D-mannoside beta 1-6N-acetylglucosaminyltransferase (N-acetylglucosaminyltransferase V) from a human lung cancer cell line.

A beta 1-6N-acetylglucosaminyltransferase (GnT-V) [EC 2.4.1.155] which catalyzes the transfer of N-acetylglucosamine from UDP-N-acetylglucosamine to alpha-D-6-mannoside has been purified up to 20,000-fold from the cultured supernatant of the QG small lung cancer cell line with a 37% yield. The isolation procedure included chromatography on phenyl-Sepharose, hydroxylapatite, UDP-hexanolamine Sepharose, and a biantennary sugar substrate (GnGn-bi-Asn) coupled to activated CH-Sepharose 4B. Sodium dodecyl sulfate gel electrophoresis under non-reducing conditions showed a single band of 73 kDa. Under reducing conditions, however, an additional component of 60 kDa was seen. Peptide mapping analysis indicated that both of these proteins were essentially identical, indicating that the 60-kDa component is probably a proteolytically cleaved form of the 73-kDa protein. Studies on the activity of the enzyme toward a variety of pyridylaminated sugars showed that the enzyme is most active toward triantennary (GnGnGn-tri-PA) and biantennary (GnGn-bi-PA) sugars. The Km values for GnGn-bi-PA and UDP-GlcNAc were 133 microM and 3.5 mM, respectively. These studies represent the first report of the enzymatic properties of a highly purified human GnT-V.

Acetylglucosamine↗
PubMed1993

[Line width addition method and its application to biologic materials emission spectrum analysis].

Using alternating current are grating spectrograph, and self-made recording microphotometer for line contour and accurate measurement of line width, we measured the concentration of Cu and Ca in serum-like synthetic standard solution with line width addition method. The experimental results had better linearity, reproducibility and higher precision compared with those by density method, suggesting that line width method is better than density method in the analysis of biologic material concentration.

Animals↗
PubMed1993

Evidence that the nodulation regulatory gene nodD3 of Rhizobium meliloti is transcribed from two separate promoters.

The Bgl II fragment carried in plasmid pMH903, which covers the nodD3 region of Rhizobium meliloti, has been sequenced. By using both S1 nuclease mapping and primer extension, two transcription start sites were demonstrated in the sequence. After the first transcription start site, there were two open reading frames (ORF) followed by the nodD3 coding sequence which was also preceded by the second promoter. The nodD3 gene under the first promoter mediated high, constitutive expression of nodC-lacZ fusion, and the gene under the second promoter required the product of nodD1 and alfalfa (Medicago sativa) seed exudate for the activation of fusion. Nodulation experiments showed that the nodD3 gene under either promoter was functional in eliciting nodules on alfalfa. The deletion of part of the two ORFs after the first promoter or deletion of the second promoter did not block the constitutive expression of nodC-lacZ fusion, whereas the deletion of the first promoter region or a polar insertion mutation between the two promoters did cause nodD3 to activate nodC only in the presence of the inducer. It indicates that nodD3 can be transcribed from the first promoter as well as from a separate second promoter.

Amino Acid Sequence↗