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Biomedical subjects

H Yu

Publications and source records attributed to H Yu.

At least 739 records · Page 41Linked to original sources
PubMed1991

[Determination of tetramethylpyrazine in traditional Chinese medicines by high performance liquid chromatography].

This paper reports a method for determining tetramethyl pyrazine in pilules, injections and extracts of Ligusticum chuanxiong by high performance liquid chromatography. The results showed the recovery rate to be higher than 97% and the coefficient of variation (CV) to be 1.39% (with in day) and 1.51% (day to day). The lowest detection amount was 0.005 micrograms. The method was easy, fast and accurate.

Chromatography, High Pressure Liquid↗
PubMed1991

Esophageal diverticulum associated with carcinoma of the esophagus--a report of four cases.

During a 25-year period, four patients with esophageal diverticulum associated with carcinoma of the esophagus underwent surgery. The results were satisfactory. The clinical features included a long history of diverticulum and the presence of a carcinoma of the esophagus in close proximity to the former. Inflammation within the diverticulum and in the mucosa around the diverticulum was noted. The closer the diverticulum to the carcinoma, the more severe the inflammation. Therefore, diverticulitis and esophagitis may be important factors leading to the development of carcinoma of the esophagus, and patients with esophageal diverticulum should be followed up regularly and the diverticulum resected as early as possible if inflammation within the diverticulum or peri-diverticular esophagitis is found.

Diverticulum, Esophageal↗
PubMed1990

Isolation of temperature sensitive mutants of Autographa californica nuclear polyhedrosis virus: phenotype characterization of baculovirus mutants defective in very late gene expression.

Temperature sensitive mutants of Autographa californica nuclear polyhedrosis virus were isolated following exposure of parental replicating virus to 5-bromo-2'-deoxyuridine. Two mutants designated ts317 and ts538 were characterized in detail. Both mutants synthesized viral DNA but were defective in infectious extracellular virus production at the nonpermissive temperature suggesting defects in late gene regulation. Pulse-labeling experiments indicated that a switch to late protein synthesis occurred but this synthesis was not maintained with either mutant since all protein synthesis was gradually inhibited by 20 hr postinfection at 33 degrees. Western blots probed with antisera directed against either extracellular virus proteins or very late proteins showed a reduction in late structural proteins, a 10-fold reduction in polyhedrin, and an absence of p10 at the nonpermissive temperature. Northern blots of total intracellular RNA showed that specific late and very late transcripts were synthesized in greatly reduced amounts at the nonpermissive temperature suggesting the absence of very late proteins was a result of inhibition of virus-specific transcription. The genetic analyses indicate that the mutations lie in two closely linked genes, both important in regulating the induction of very late transcription and translation.

Animals↗
PubMed1990

Activation of adenosine receptors induces c-fos, but not c-jun, expression in neuron-glia hybrids and fibroblasts.

Extracellular adenosine acts through specific cell surface receptors to modulate numerous physiological processes in both the CNS and peripheral tissues (e.g. neurotransmitter release and blood flow). Activation of A1 or A2 adenosine receptors leads to decreased or increased intracellular cAMP levels, respectively. Fos and Jun are nuclear proto-oncogene products, which, like cAMP, appear to act as intermediates in a number of signal transduction pathways. Since increases in both adenosine release and Fos and Jun expression occur in the brain following seizures, we wanted to determine whether Fos and Jun induction might occur as a result of adenosine receptor activation. 3T3 fibroblasts and NG108-15 neuroblastoma-glioma hybrid cells were chosen for study, since they were known to respond to adenosine agonists with changes in cAMP levels. The membranes of NG108-15 cells were shown to have A2-like binding activity in a competitive binding assay. Cultures of each cell line were treated with the adenosine agonists, CHA (A1-selective) and NECA (non-selective adenosine agonist). Both lines responded with a concentration-dependent transient increase in c-fos, but not c-jun, mRNA content after treatment with either agonist. The kinetics of the response were much more rapid for 3T3 cells (peak between 15 and 30 min) than for NG cells (peak between 60 and 90 min). The slower, more prolonged response in the NG108-15 cells is more similar to the time interval between adenosine release and the peak of c-fos mRNA induction in brains of animals following the administration of seizure-promoting drugs.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Selective killing of tumor cells in vitro by an immunotoxin composed of ricin and monoclonal antibody against Ia antigen.

A monoclonal antibody (MAb-HB55) directed against a HLA class II antigen (Ia), was purified by DE-52 chromatography. The purified MAb contained less than 5% impure protein detected by SDS-PAGE. Ricin was conjugated with the MAb via a disulfide bond to construct an immunotoxin (ricin-HB55). The concentration causing fifty percent growth inhibition (IC50) was 2 x 10(-11)M for the Raji cells. In contrast, the IC50 for Molt-4 and K562 cells was 100 times higher than that for the Raji cells. B lymphocytes separated from peripheral blood lymphocytes by nylon wool were selectively killed by the conjugate, but T lymphocytes were not apparently affected. Our results demonstrate that the immunotoxin is selectively cytotoxic to Raji cells and B-cells, and may have potential for purging malignant cells from bone marrow of patients with B-cell leukemia and lymphoma.

Ammonium Chloride↗
PubMed1990

Sequence analysis of ripening-related cytochrome P-450 cDNAs from avocado fruit.

The ripening of avocado fruit is associated with the expression of a number of mRNAs concomitant with overt changes in texture and flavor. Two overlapping cDNAs for a mRNA that accumulates during ripening were identified. Sequence analysis of these two cDNAs revealed a polypeptide of 471 amino acids with characteristics of a typical P-450: an N-terminal hydrophobic membrane anchor, a conserved heme-binding domain in the C-terminal region, and patches of similarity to various P-450 family members. Further evidence that this polypeptide represents a cytochrome P-450 oxidase comes from the recent isolation and characterization of a cytochrome P-450 from ripe avocado mesocarp [O'Keefe, D. P. & Leto, K. J. (1989) Plant Physiol. 89, 1141-1149]. The N terminus of the predicted polypeptide in the cDNAs is identical to the N terminus of the purified avocado P-450. Gel blot analysis of RNA from fruit at various stages of ripening showed the accumulation of an 1800-nucleotide P-450 mRNA that hybridized to the P-450 cDNA. The P-450 protein predicted by the avocado cDNA sequence shares less than 40% positional identity with any known P-450 gene family. We propose therefore that it be placed in a separate family, P450LXXI, and that the corresponding gene from avocado be named cyp71A1.

Amino Acid Sequence↗
PubMed1990

cDNA sequence for human erythrocyte ankyrin.

The cDNA for human erythrocyte ankyrin has been isolated from a series of overlapping clones obtained from a reticulocyte cDNA library. The composite cDNA sequence has a large open reading frame of 5636 base pairs (bp) with the complete coding sequence for a polypeptide of 1879 amino acids with a predicted molecular mass of 206 kDa. The derived amino acid sequence contained 194 residues that were identical to those obtained by direct amino acid sequencing of 11 ankyrin proteolytic peptides. The primary sequence contained 23 highly homologous repeat units of 33 amino acids within the 90-kDa band 3 binding domain. Two cDNA clones showed evidence of apparent mRNA processing, resulting in the deletions of 486 bp and 135 bp, respectively. The 486-bp deletion resulted in the removal of a 16-kDa highly acidic peptide, and the smaller deletion had the effect of altering the COOH terminus of the molecule. Radiolabeled ankyrin cDNAs recognized two erythroid message sizes by RNA blot analysis, one of which was predominantly associated with early erythroid cell types. An ankyrin message was also observed in RNA from the human cerebellum by the same method. The ankyrin gene is assigned to chromosome 8 using genomic DNA from a panel of sorted human chromosomes.

Amino Acid Sequence↗
PubMed1990

Prevalence survey of cytomegalovirus infection in children in Chengdu.

Cytomegalovirus (CMV) is a common worldwide perinatal infection. Although usually asymptomatic, it may cause deafness in up to 15% of these infants. A cross-sectional study was performed to determine the age-specific prevalence of CMV seropositivity in Chinese children and to determine if any risk factors for infection could be identified. In a two-stage sampling procedure, nine districts were randomly selected from 70 citizenship districts in Chengdu, Sichuan Province, People's Republic of China. Then, 1,950 households were randomly selected from 11,886 households and interviewed. Blood was obtained from all children aged less than seven years and assayed using an enzyme-linked immunosorbent assay method. A subgroup of sera was retested at the research laboratory and also sent to the National Reference Laboratory in Beijing. Kappa values for the test agreement with the reference laboratory and retesting within the study laboratory were 0.94 and 0.86, respectively. Seropositivity averaged 52% in those aged less than one year and 60% in those between four and seven years. A higher rate of seropositivity was observed in urban versus rural children (odds ratio (OR) = 2.55), breast feeding in urban areas only (OR = 1.87), and day care versus home care setting (OR = 1.59). High CMV seroprevalence, even in the first year of life, was observed in this population of well children in Chengdu, China. An association was observed between seroprevalence and residence, method of feeding, and day care attendance.

Bottle Feeding↗
PubMed1990

Density-dependent nerve growth factor regulation of Gs-alpha RNA in pheochromocytoma 12 cells.

Nerve growth factor (NGF) affects levels of the alpha subunit of the stimulatory G protein (Gs-alpha) in pheochromocytoma 12 cells in a bidirectional, density-dependent manner. Cells grown at high density responded to NGF treatment with increased levels of Gs-alpha mRNA and protein. Conversely, in cells grown in low-density cultures, levels of this mRNA were lowered by NGF treatment.

Adrenal Gland Neoplasms↗
PubMed1990

Primary lymphoma of the lung.

Two cases of primary lymphoma of the lung are reported, both of which were misdiagnosed preoperatively as bronchogenic carcinoma before undergoing successful resection. Accurate diagnosis was obtained after operation. These two patients were in good condition after a short period of follow-up. A discussion is presented concerning diagnosis, treatment and prognosis. Also, we point out the reason why so few primary lymphomas of the lung are reported: the mass of the lymphoma is typically so large that surgeons may consider it to be lung cancer in a late stage and thus abandon surgical intervention, or it may be erroneously diagnosed pathologically as undifferentiated small cell carcinoma of the lung.

Adult↗
PubMed1990

Study of SOS-inducing kinetics and inhibitory effect on induction of Escherichia coli.

It was found that modified pulse induction could produce SOS responses of the sfi gene in 15 minutes. The responses peaked at 30-60 minutes and were twice as strong as those by persistent induction. The modified pulse induction could therefore more truly reflect the inducing effect. However, the SOS-inducing kinetics of MMC and 4NQO was not identical suggesting distinct kinetic patterns of induction by different mutagens. A suppressive effect on 4NQO-induced SOS response by cinnamic aldehyde and diallyl trisulfate was also observed. The effect might be due to an interference with the metabolic activation of 4NQO or breakdown of 4NQO by the bacteria.

4-Nitroquinoline-1-oxide↗
PubMed1990

[Evaluation of RPHA fecal occult blood test in screening for colorectal cancer].

Evaluation of reverse passive hemagglutination (RPHA) fecal occult blood (FOB) test in screening for colorectal cancer was carried out in a group of subjects (3034 persons) with history of rectal polyp and ulcer. All subjects were examined by 60 cm fiberoptic colonoscopy, RPHA and benzidine (BT) FOB tests. Among this high risk population, 10 cases of colorectal cancer and 1 case of rectal carcinoid were detected by colonoscopy and pathology. Regarding the findings under fiberoptic colonoscopy as a reference standard, the sensitivity of RPHA and BT in screening for colorectal cancer was 63.6% and 72.7%; the specificity was 81.9% and 61.7%; the general indicator--Youden index was 0.46 and 0.34, respectively. In 7 cases of colorectal cancer with both FOB tests positive, 5 (71%) had lesions in early stages (Dukes A and B). The results indicate that comparing with BT, RPHA has slightly lower sensitivity but higher specificity. RPHA fecal occult blood test could be used as preliminary screening for colorectal cancer.

Adenocarcinoma↗