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Biomedical subjects

Y Lu

Publications and source records attributed to Y Lu.

At least 829 records · Page 46Linked to original sources
PubMed1994

Prediction of pain center treatment outcome for geriatric chronic pain patients.

OBJECTIVE: Geriatric chronic pain patients (age 65 and over) form an increasing percentage of the pain center treatment population. It is therefore important to be able to predict pain center treatment success or failure for these patients; this is the first study to address this concern. DESIGN: Chronic pain patients rated themselves at pain center admission and discharge on 43 rating scales for the areas of pain, functional status, behavioral variables, and other pain center modification categories. The 43 scores at admission were used as potential predictors, while the 43 change scores (from admission to discharge) were the outcome measures to be predicted. Additional possible predictors were 16 other variables that are considered prognostic of treatment outcome, including age, number of surgeries, and prior occupational level. The statistical analysis consisted of a five-step procedure: (a) mathematical techniques were used to remove redundant outcome measures; (b) each of the remaining outcome variables was correlated with the full set of predictor variables; (c) regression techniques were used to predict the outcome variables; (d) these outcome variables were combined into independent factors using factor analysis; and (e) regression techniques were used to predict the factors. RESULTS: The variable-reduction technique was successful in removing 26 of the 43 outcome variables. Factor analysis of change scores of the remaining variables resulted in four factors, which were identified as change in activity, change in pain and behavior, change in constant pain, and change in attitude to pain center goals. The analysis showed that the best predictor of a variable's change score was the initial level of that variable. Regression analysis, using all variables as predictors except initial level, found a number of statistically significant predictors. However, no predictor variable, alone or in combination, was able to account for > 30% of the variance of any outcome measure. CONCLUSION: These results indicate that we cannot as yet predict geriatric pain center treatment outcome. Potential reasons for these results are discussed.

Aged↗
PubMed1994

Retreatment of intracranial gliomas.

Although intracranial gliomas carry a poor long-term prognosis, retreatment at the time of tumor progression may prolong survival and maintain or improve the quality of life. Thirty-three patients who underwent retreatment with surgery, radiotherapy, and chemotherapy were reviewed retrospectively. Median survival after initiation of retreatment was 8 months for glioblastoma, 13 months for anaplastic astrocytoma, 22 months for astrocytoma, and 47 months for oligodendroglioma/mixed glioma. Survival was significantly better for younger patients and for those with better functional status. One third of patients were neurologically improved by surgery. Surgical morbidity was minimal (2.1%); there was no surgical mortality. Chemotherapy and radiotherapy produced expected adverse reactions. Retreatment of intracranial gliomas carries acceptable risk and is beneficial in selected patients. Decisions regarding retreatment must be carefully individualized with consideration of the quality of life and the wishes of the patient and family.

Adult↗
PubMed1994

Particle assembly and Vpr expression in human immunodeficiency virus type 1-infected cells demonstrated by immunoelectron microscopy.

The 96 amino acid viral protein R (Vpr) of human immunodeficiency virus type 1 (HIV-1) was detected during virus assembly in intracellular vacuoles and at the plasma membrane on peripheral blood mononuclear cells. In both immature and mature virus particles, Vpr was located immediately beneath the viral envelope, colocalizing with the core structural protein, Gag p24. Vpr was present in intracellular HIV-1 wild-type virions at 50% of the level found in extracellular HIV-1 particles. Cells infected with HIV-1 strains with C-terminal truncations of Vpr manifested a different pattern of Vpr expression. A mutant with an alteration of amino acids 79 to 85 exhibited a 23% reduction in total levels of Vpr expression, but a marked accumulation of Vpr in intracellular rather than extracellular virions. A mutant with the last 17 amino acids of Vpr deleted expressed only 10% of wild-type levels of Vpr. These observations indicate that Vpr is incorporated into virions from the cytoplasmic aspect of either the vacuolar or plasma membrane. Furthermore, the proportion of Vpr on intracellular compared to extracellular virions is affected by a specific locus within the protein.

Amino Acid Sequence↗
PubMed1994

Interactions of intestinal mediators in the mode of action of cholera toxin.

Cholera toxin (CT) and prostaglandin E2 (PGE2) increased the synthesis of 3',5'-cyclic adenosine monophosphate (cAMP) in rabbit intestinal mucosa, which appeared to be responsible for inducing the release of 5-hydroxytryptamine (5-HT) from enterochromaffin cells into the intestinal lumen. With isolated intestinal cells, CT induced the synthesis of PGE2 more efficiently from epithelial cells than from lamina propria cells; however, the basal amount of this eicosanoid produced by lamina propria cells was approximately six-fold more than that formed by the epithelial cells. The CT-induced stimulation of arachidonate metabolism appeared to be generalised in nature, as PGF2 alpha and leukotrienes were synthesised in addition to PGE2. Injection of dibutyryl cAMP into the intestinal lumen in vivo markedly reduced both basal levels of PGE2, as well as CT-induced levels of PGE2, released into the luminal fluid. Similarly, when biopsy samples of tissue from rabbit intestinal loops, challenged in vivo with dibutyryl cAMP, were washed and incubated in vitro, the amount of PGE2 synthesis remained below basal levels. In contrast, when biopsy samples of normal small intestinal tissue were exposed in vitro to dibutyryl cAMP, PGE2 synthesis increased. Thus, cAMP appeared to down-regulate the levels of intestinal eicosanoids in vivo, despite its innate capacity to evoke PGE2 synthesis from mucosal tissue in vitro. Thus, the data indicate that CT-induced mediators exhibit interactive effects that alter their cellular concentrations, that in turn could affect the biological responses.

Animals↗
PubMed1994

Regulation of the Bacillus subtilis pyrimidine biosynthetic (pyr) gene cluster by an autogenous transcriptional attenuation mechanism.

A complete transcript of the Bacillus subtilis pyr operon contains the following elements in 5' to 3' order: a 151-nucleotide (nt) untranslated leader; pyrR, encoding a 20-kDa protein; a 173-nt intercistronic region; pyrP, encoding a 46-kDa protein; a 145-nt intercistronic region; and eight overlapping cistrons encoding all of the six enzymes for de novo pyrimidine biosynthesis. Transcription is controlled by the availability of pyrimidines via an attenuation mechanism. There are three transcription terminators within the operon, each of which is preceded by another stem-loop structure, the antiterminator, whose formation would prevent formation of the terminator stem-loop. These are located in the leader, the pyrR-pyrP intercistronic region, and the pyrP-pyrB intercistronic region. Northern (RNA) blot analysis has identified transcripts of lengths which coincide with termination at these proposed attenuation sites and whose relative abundances vary in the expected pyrimidine-dependent manner. Each antiterminator contains a 50-base conserved sequence in its promoter-proximal half. Various transcriptional fusions of the pyr promoter and surrounding sequences to promoterless reporter genes support an attenuation mechanism whereby when pyrimidines are abundant, the PyrR protein binds to the conserved sequence in the pyr mRNA and disrupts the antiterminator, permitting terminator hairpin formation and promoting transcription termination. Deletion of pyrR from the chromosome resulted in the constitutive, elevated expression of aspartate transcarbamylase, which is encoded by pyrB, the third gene in the operon. Complementation of an E. coli upp mutant, as well as direct enzymatic assay, has demonstrated that pyrR also confers uracil phosphoribosyltransferase activity. Analysis of pyrR and upp deletion mutants demonstrated that upp, not pyrR, encodes the quantitatively important uracil phosphoribosyltransferase activity. The pyrP gene probably encodes an integral membrane uracil permease.

Amino Acid Sequence↗
PubMed1994

Identification of a putative alternate sigma factor and characterization of a multicomponent regulatory cascade controlling the expression of Pseudomonas syringae pv. syringae Pss61 hrp and hrmA genes.

The Pseudomonas syringae hrp and hrmA genes controlling pathogenicity and elicitation of the hypersensitive response and the avr genes controlling host range have been shown previously to be regulated by carbon, nitrogen, pH, osmolarity, and hypothetical plant factors. In P. syringae pv. syringae Pss61, inactivation of hrp complementation groups II and XIII reduced expression of a plasmid-borne hrmA'-lacZ fusion. The hrp regions II and XIII were cloned on separate plasmids and shown to enhance the activity of the hrmA promoter in Escherichia coli MC4100 transformants at least 100-fold. The nucleotide sequence of region XIII revealed two open reading frames (hrpR and hrpS) whose deduced products share homology with P. syringae pv. phaseolicola NPS3121 HrpS and are both related to the NtrC family of two-component signal transduction systems. HrpR and HrpS differ from most members of the protein family by lacking an amino-terminal domain which modulates the regulatory activity. A single open reading frame, hrpL, whose product shares homology with AlgU, a putative alternate sigma factor of P. aeruginosa, as well as with the related alternate sigma factors was identified within region II. Key domains are partially conserved. Inactivation of hrpS in Pss61 repressed expression of a plasmid-borne hrpL'-lacZ fusion carried by pYXPL1R, and transformation of MC4100(pYXPL1R) with a plasmid carrying hrpRS increased hrpL promoter activity at least 200-fold. Neither hrpS nor hrpR, when cloned on separate plasmids, activated the hrpL promoter activity individually. The expression of hrpL when directed by a lac promoter was sufficient to express a set of plasmid-borne hrmA'-, hrpJ'-, and hrpZ'-lacZ fusions independently of other hrp genes. The results indicate that hrpRS and hrpL are part of a regulatory cascade in which HrpR and HrpS activate expression of hrpL and HrpL, a putative sigma factor, induces expression of HrpL-responsive genes.

Amino Acid Sequence↗
PubMed1994

A strand bias occurs in point mutations associated with variant surface glycoprotein gene conversion in Trypanosoma rhodesiense.

We previously described a bloodstream Trypansoma rhodesiense clone, MVAT5-Rx2, whose isolation was based on its cross-reactivity with a monoclonal antibody (MAb) directed against a metacyclic variant surface glycoprotein (VSG). When the duplicated, expressed VSG gene in MVAT5-Rx2 was compared with its donor (basic copy) gene, 11 nucleotide differences were found in the respective 1.5-kb coding regions (Y. Lu, T. Hall, L. S. Gay, and J. E. Donelson, Cell 72:397-406, 1993). Here we describe a characterization of two additional bloodstream trypanosome clones, MVAT5-Rx1 and MVAT5-Rx3, whose VSGs are expressed from duplicated copies of the same donor VSG gene. The three trypanosome clones each react with the MVAT5-specific MAb, but they have different cross-reactivities with a panel of other MAbs, suggesting that their surface epitopes are similar but nonidentical. Each of the three gene duplication events occurs at a different 5' crossover site within a 76-bp repeat and is associated with a different set of point mutations. The 35, 11, and 28 point mutations in the duplicated VSG coding regions of Rx1, Rx2, and Rx3, respectively, exhibit a strand bias. In the sense strand, of the 74 total mutations generated in the three duplications, 54% are A-to-G or G-to-A (A:G) transitions and 7% are C:T transitions, while 26% are C:A transversions and 13% are C:G transversions. No T:G or T:A transversions occurred. Possible models for the generation of these point mutations are discussed.

Amino Acid Sequence↗
PubMed1994

[Studies on the constituents of the roots of Acorus calamus L].

A new tricyclic sesquiterpene, named calamenone (1), and two known sesquiterpenes, calamendiol (2) and isocalamendiol (3), were isolated from the roots of Acorus calamus L. The structure of the new compound was elucidated on the basis of spectral and X-ray diffraction data.

Drugs, Chinese Herbal↗
PubMed1994

A clinical study on the postoperative prognosis of 168 cases of surgical hyperbilirubinemia.

It's universally acknowledged that the mortality rate of postoperative patients with obstructive jaundice is higher than that of the non-icteric. Opinions, however, differ as to whether the mortality rate goes up with the worsening of jaundice. Some even regard hyperbilirubinemia as a contraindication in operation. The present article through a clinical research of 168 cases suggested that postoperative mortality registered no increase because of bilirubin level in plasma and the degree of severity of bilirubinemia was not a major factor affecting the postoperative prognosis. The 4 preoperative complications: hypoproteinemia, hepatocirrhosis, portal hypertension and acute cholangitis were responsible for postoperative prognosis, the conclusion is hyperbilirubinemia is not a contraindication in operation. A great portion of the patients should be given active operation to intercept persistent injury on liver and prevent the occurrence of acute cholangitis. To reduce the postoperative mortality, the treatment to be adopted is not to arrange biliary drainage before operation but to improve the patients general conditions by eliminating the complications mentioned above.

Adult↗
PubMed1994

[Detection on BCR-ABL fusion gene in Ph1 chromosome positive leukemia by "nested" retrotranscriptase/polymerase chain reaction].

By using "nested" retrotranscriptase/polymerase chain reaction (RT/PCR) technique, we determined the expression patterns of the BCR-ABL fusion gene resulting from the chromosomal translocation t (9; 22) in leukemias with Ph1 chromosome. Three distinct isoforms of fusion gene transcripts were discovered: ela2, b2a2 and b3a2. In 10 cases of chronic myelogenous leukemia (CML), only two types (b2a2 and b3a2) were observed. However, in 8 cases of Ph1 chromosome positive acute lymphoblastic leukemia (Ph1 + ALL), all three types were detected, including two cases characterized by the coexistence of ela2 and b2a2 or b3a2 types. Moreover, the RT/PCR procedure established in the present study proved to be a very sensitive method, allowing the detection of one leukemic cell among 10(5)-10(6) normal cells. Thus, a positive RT/PCR result was obtained in two Ph1 + ALL cases just after chemotherapy-induced clinical remission (CR), suggesting the presence of residual disease. One case remained RT/PCR positive four months after achieving CR and relapsed in the fifth month, while the other case converted to RT/PCR negative eight months later and is now in CR for 18 months. Therefore the detection of BCR-ABL fusion gene is of importance not only in the study of the pathogenesis of Ph1 + leukemias but also in their diagnosis and monitoring of minimal residual disease during CR.

Adolescent↗
PubMed1994

[Study on polymorphism of ribosomal RNA gene in Chinese Hans and Yis].

In the secondary constriction region of the short arm of human group D and group G acrocentric chromosomes there are tandemly repeated sequences of transcriptable segments and non-transcriptable spacers of rRNA genes. In the non-transcriptable spacer segments there is a polymorphic region with length variation. This paper reports the results obtained when the BamHI digested products of genomic DNA from 36 cases of Han nationality and those from 40 cases of Yi nationality were probed with a cDNA subprobe, pA(BE), which corresponds to the downstream one third of the 28S rRNA gene and is 1.6kb long with BamHI and EcoRI restriction sites at its two terminal respectively, using Southern blotting and molecular hybridization techniques. A total of 10 different restriction fragments were detected. Four fragments (7.9, 4.9, 4.0 and 1.2 kb) were seen in all subjects tested and the frequencies of six other polymorphic fragments in Hans and Yis (10.0, 9.4, 8.5, 6.7 6.0 and 3.0 kb) showed no significant difference when compared to each other. From the 10 different patterns of combination of restriction fragments four of them (1HY, 2HY, 3HY and 4HY) were detected in both Hans and Yis with no significant difference between their respective frequencies. Four other patterns (5H, 6H, 7H and 8H) were only seen in Hans with individual frequencies not high enough to be statistically significant. However, the statistical test for the combined frequencies of these four patterns showed highly significant difference between Hans and Yis (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

China↗
PubMed1994

[Immunohistochemical observation of anti-human hepatocellular carcinoma monoclonal antibody HL2 in cancers].

Molecular weight of human hepatocellular carcinoma (HCC)-associated antigen-HL2 antigen was detected to be about 50,000 dalton by SDS-PAGE and Western blot. One hundred and twenty-seven paraffin sections of cancers and pathological liver tissue were tests by ABC immunohistochemical staining. MAb HL2 reacted with 62.7% HCC and also with 8 of the 10 stomach carcinomas but only with a few other digestive system carcinomas (pancreas carcinoma, rectum carcinoma and duodenum carcinoma) and hepatitis. MAb HL2 was negative in hepatocirrhosis and other tumors (vesica carcinoma, skin carcinoma, breast carcinoma, neurogliocytoma and carcinoma of the lung). The results suggest that MAb HL2 has values in diagnosis of HCC and differential diagnosis between HCC and other tumours. HL2 antigen might be a new tumor-associated antigen (TAA). Further study of HL2 antigen will significantly show the actions of TAA in the occurrence and development of tumor.

Antibodies, Monoclonal↗
PubMed1994

[Studies on the molecular evolution of apolipoprotein multigene family].

The apolipoprotein genes represent a large family of genes encoding various binding proteins for plasma lipid transport. Because of their long divergence history, it is not known whether and how these genes have evolved through gene duplication from a common ancestor. To test this possibility and reconstruct a reliable phylogenetic tree, a simple method to evaluate the branch length and its divergence time in unrooted parsimony tree under the condition of non-even evolutionary rate was developed. The tree built from the 26 apolipoprotein sequences by above method clearly shows: (1) The common ancestor of ApoA-I ApoA-II, ApoA-IV, ApoE may appear 460 million years ago in an ordovician vertebrate which may be related with the major apolipoprotein LAL1 and LAL2 in Lamprey from the evidence of sequence alignment; (2) The central role of different selection pressure upon the ancestor gene of apolipoprotein made them evolved into different subgroups; (3) The high evolution rate in rodent ApoE molecules may be related with the existence of a large amount of hidden substitutions and the disruption of synonym codon usage clock in their genome; (4) The evolutionary rate of various branches in parsimony tree is significantly different in which the average UEP of ApoA-I, ApoA-IV is 2.0 MY, ApoA-II 1.7MY, ApoE 2.4MY; (5) The receptor domain in ApoE seems to be more conservative than other fragments. These data suggest a long, complex evolutionary history for apolipoprotein genes in which the gene duplication events of different origins took place.

Amino Acid Sequence↗
PubMed1994

[Long-term results of radial keratotomy (RK)].

Among myopic patients performed RK with operative parameters stipulated by the authors' own computer software, 77 cases (152 eyes) were followed up over 1 year to find that 68% of the eyes with preoperative myopia of < or = -6.00DS attained visual acuity of 1.0 or better, and incision depths over 80% of the corneal thickness were conducive to long-term good effects: hence accurate determination of the corneal thickness was very important. In view of the limitations of RK, the authors suggested indications and contraindications for the procedure.

Adult↗
PubMed1994

Evidence for retinoblastoma protein (RB) dependent and independent IFN-gamma responses: RB coordinately rescues IFN-gamma induction of MHC class II gene transcription in noninducible breast carcinoma cells.

The class II major histocompatibility (MHC) genes encode cell surface heterodimers that present processed antigen to CD4 positive T-cells. The class II genes are expressed constitutively on B-cells and can be induced by IFN-gamma on a variety of other cell types. Because the class II genes are aberrantly expressed on many mesenchymal tumors, which are frequently defective for the retinoblastoma tumor suppressor protein (RB), we investigated the role of RB in the regulation of HLA-DR and -DP. The RB defective breast carcinomas cell line, MDA-468-S4 (S4), as well as S4 subclones reconstituted with RB coding sequences under the control of a zinc inducible promoter, were treated with IFN-gamma and examined for DR and DP expression. Surface DR is not inducible in S4 cells, but inducibility is rescued by RB. DP is only slightly inducible in S4, but inducible to a much higher level in the RB positive subclones of S4. IFN-gamma induction of DR and DP mRNAs are correspondingly dependent on RB. IFN-gamma receptors are present on S4 cells, and the guanylate binding protein and ICAM-1 genes respond to IFN-gamma, ruling out the possibility that all IFN-gamma signal transduction pathways are defective in S4 cells. These data indicate RB regulates the coordinate response of class II genes to IFN-gamma. Possible roles for RB in this process are discussed, as well as the role of the class II-noninducible phenotype in tumor rejection.

Breast Neoplasms↗