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Biomedical subjects

Q Zhu

Publications and source records attributed to Q Zhu.

At least 235 records · Page 13Linked to original sources
PubMed1995

Accurate in vitro transcription from circularized plasmid templates by plant whole cell extracts.

A convenient in vitro transcription system using monocot and dicot whole cell extracts and circular DNA templates has been developed. The system consists of incubating template and whole cell extract to generate initiation complexes, followed by addition of nucleotide triphosphates to support elongation, and primer extension assay to detect authentic transcripts. This in vitro transcription system required circularized templates and was essentially inactive with linearized templates. Accurate in vitro transcription of a rice phenylalanine ammonia-lyase (PAL) promoter-beta-glucuronidase (GUS) gene fusion and a tobacco sesquiterpene cyclase promoter-GUS gene fusion was examined in their homologous whole cell extracts, and the optimal concentrations for several reaction components, including DNA template, whole cell extract, monovalent and divalent cations, were determined for specific initiation from the in vivo start site. Transcription was inhibited by low concentrations of alpha-amanitin, demonstrating that the reaction was mediated by RNA polymerase II. Accurate transcription initiation was dependent on the TATA-box motif within the respective promoters. Based on the effect of delayed addition of sarkosyl at a concentration sufficient to inhibit transcription initiation but not elongation, three to four rounds of transcription were initiated in standard assays.

Base Sequence↗
PubMed1995

TATA box and initiator functions in the accurate transcription of a plant minimal promoter in vitro.

The functional architecture of the proximal region of a rice phenylalanine ammonia-lyase (PAL) promoter was analyzed by transcription of PAL-beta-glucuronidase (GUS) templates by whole-cell extracts of rice cell suspension cultures. The promoter 5' truncated to position -35 was sufficient for accurate initiation of basal transcription. Substitution of the TATTTAA sequence between positions -35 and -28 with GCGGGTT or 2-bp substitutions to give TCGTTAA and TATGGAA inactivated the minimal promoter. Moreover, the function of the TATTTAA sequence was dependent on its position relative to the initiation site; hence, this element is an authentic TATA box essential for RNA polymerase II-dependent transcription. Substitutions in the TCCAAG initiator cis element (-3 to +3) at the -1 (C to A or G) and +1 (A to C or T) residues caused inaccurate initiation, whereas mutations at the other residues of this conserved element or sequence substitutions between the TATA box and initiator had little effect. TATA box and initiator functions were confirmed by analysis of the effects of promoter mutations on expression in stably transformed rice cell suspensions and plants. We concluded that the proximal region of the PAL promoter has a simple functional architecture involving a TATA box appropriately positioned upstream of the initiator. Transcription of derivatives of such minimal promoters by highly active cell extracts should allow molecular analysis of functional interactions between specific cis elements and cognate trans factors.

Base Sequence↗
PubMed1995

Measurement and correction of ultrasonic pulse distortion produced by the human breast.

Ultrasonic wavefront distortion produced by transmission through breast tissue specimens was measured in a two-dimensional aperture. Differences in arrival time and energy level between the measured waveforms and references that account for geometric delay and spreading were calculated. Also calculated was a waveform similarity factor that is decreased from 1.0 by changes in waveform shape. For nine different breast specimens, the arrival time fluctuations had an average (+/- s.d.) rms value of 66.8 (+/- 12.6) ns and an associated correlation length of 4.3 (+/- 1.1) mm, while the energy level fluctuations had an average rms value of 5.0 (+/- 0.5) dB and a correlation length of 3.4 (+/- 0.8) mm. The corresponding waveform similarity factor was 0.910 (+/- 0.023). The effect of the wavefront distortion on focusing and the ability of time-shift compensation to remove the distortion were evaluated by comparing parameters such as the -30-dB effective radius, the -10-dB peripheral energy ratio, and the level at which the effective radius departs from an ideal by 10% for the focus obtained without compensation, with time-shift estimation and compensation in the aperture, and with time-shift estimation and compensation performed after backpropagation. For the nine specimens, the average -10-dB peripheral energy ratio of the focused beams fell from 3.82 (+/- 1.83) for the uncompensated data to 0.96 (+/- 0.18) with time-shift compensation in the aperture and to 0.63 (+/- 0.07) with time-shift compensation after backpropagation. The average -30-dB effective radius and average 10% deviation level were 4.5 (+/- 0.8) mm and -19.2 (+/- 3.5) dB, respectively, for compensation in the aperture and 3.2 (+/- 0.7) mm and -22.8 (+/- 2.8) dB, respectively, for compensation after backpropagation. The corresponding radius for the uncompensated data was not meaningful because the dynamic range of the focus was generally less than 30 dB in the elevation direction, while the average 10% deviation level for the uncompensated data was -4.9 (+/- 4.1) dB. The results indicate that wavefront distortion produced by breast significantly degrades ultrasonic focus in the low MHz frequency range and that much of this degradation can be eliminated using wavefront backpropagation and time-shift compensation.

Adolescent↗
PubMed1995

Correlation distance measurements of the female breast.

Ultrasonic waves propagating through soft tissue experience wavefront distortion. Adaptive wavefront compensation algorithms attempt to correct such distortion. A valuable design parameter is the isoplanatic patch size of the imaging medium. Its lateral extent is the FWHM of the correlation function. The range extent is defined similarly. The significance of the isoplanatic patch is that a new wavefront correction vector must be obtained whenever the ultrasound beam is moved a patch length. This paper reports measurements of wavefront correlation functions as well as statistics of the lateral correlation distance rho d (half the FWHM) within the female breast obtained from a population of 22 women (44 breasts) and measured at 3 and 4 MHz with a large acoustic aperture (9.6 cm). A set of complex wavefronts radiated from single pointlike sources was measured from the opposing side of the breast. The propagation distance was 12 cm. rho d is the distance between two sources at which the correlation between their wavefronts drops to 0.5. The mean value at 3 MHz was found to be less than 1.5 mm for the premenopausal dense breast, 2.5 mm for the premenopausal fatty breast, and 2.0 mm for the postmenopausal breast. The mean value dropped by a factor of 2 at 4 MHz for a group consisting of premenopausal fatty and postmenopausal breasts.

Adult↗
PubMed1995

A new method for early diagnosis of carcinoma in bile duct-sonography of common bile duct before and after injection of ceosunin.

42 cases of dilatation (7-15 mm) of extrahepatic bile duct after ceosunin injection (cholagogic method) were observed ultrasonographically. Among the 18 cases of testified obstructive lesions of the bile duct, 13 (72%) showed widening of the bile duct with an increase of calibre from 9.8 mm to 11.7 mm, 3 (16%) had no obvious change, and 2 (12%) shrank. Among the 24 cases of non-obstruction 22 (92%) shrank with a decrease calibre from 9.6 mm to 6.3 mm, and 2 (8%) showed no obvious change. After receiving cholagogue, 9 cases of periampullary carcinoma in the obstructive group were confronted with widening of the bile duct calibre. After longitudinal and transverse rotation scanning method was used, 8 of the 9 cases had their tumor mass visualized. Combined cholagogic and rotation scanning methods raised the lesion manifestation rate of lower bile duct from 41% to 88%. A dilated bile duct unable to show shrinkage of calibre after cholagogue injection is believed to be a criterion for judging the presence of a suspicious case of bile duct obstruction. This criterion has a sensitivity of 89%, specificity of 92%, and accuracy of 90%.

Adenocarcinoma↗
PubMed1995

[Biomechanical evaluation of cervical stability with Halifax clamp after bilateral facetectomy].

With nine fresh adult cervical spine specimens (C3-T1), the three-dimensional motions of C4-5 segment were analysed to evaluate the immediate stability following bilateral facetectomy, Halifax clamp and wire fixation. The results showed that the stability with Halifax clamp was greater than that of the intact state in flexion, extension and lateral bending, but the same as in axial rotation. The stability with wire fixation was greater than that in flexion and equal to that in extension, lateral bending and axial rotation. The ROMs with Halifax Clamp were less than those with wire fixation in flexion, extension and lateral bending, but close to in axial rotation.

Adult↗
PubMed1995

[Detection and quantification of lipoprotein (a) in atherosclerotic lesions of human aorta].

Lipoprotein(a) [Lp(a)] represents an independent risk factor for atherosclerotic disease. In the present study, the extent to which Lp(a) accumulated in normal and various degrees of atheromatous lesions and the distribution pattern of Lp(a) in these lesions have been studied in thoracic aorta from the autopsy tissues by means of immunohistochemistry, immunoelectronic microscopy, enzyme-linked immunosorbent assay and computer-assisted image processing. Lp(a) was found to be localized preferentially in lesion areas and had its own distribution pattern in each kind of lesion. Lp(a) associated primarily with extracellular matrix and was detected in only a small number of foamy cells. Apolipoprotein B was also detected, whose staining pattern was always found to be congruent with that of Lp(a). This suggests that the immunoreactivity of apoB is related to the presence of Lp(a) at least in part, since Lp(a) possesses apoB in addition to apo(a). It was concluded that both low density lipoprotein and lipoprotein(a) play an important role in the pathogenesis of atherosclerosis.

Adolescent↗
PubMed1995

[Congenital pulmonary lymphangiectasis].

Six rare cases of congenital pulmonary lymphangiectasis were presented. The macroscopic characteristic of the lungs was honeycomb appearance due to extreme dilatation of the lymphatic spaces in the subpleural, interlobular, peribronchial and perivascular connective tissue. They had thin walls lined by endothelium. The dilated lymphatics may be due to congenital developmental defects or obstruction of major lymphatics, but they appeared to be associated only with pulmonary venous hypertension.

Female↗
PubMed1995

[Evaluation of operative corrigent degree of scoliosis by improved Cobb's angle degree of preoperative suspensive roentgenogram].

To achieve best operative result in correction of scoliosis, and avoid complications of the nerve system due to excess correction, we compared the statistical results of modified Cobb's degree of preoperative suspensive roentgenogram and operative corrigent degrees of 331 patients with scoliosis, including 219 with idiopathic scoliosis. The modified Cobb's degrees of the whole group was 20.15 +/- 9.41 in suspension, the operative corrigent degree was 35.34 +/- 13.05, and the operation-suspension difference was 14.62 +/- 11.02. Referring to idiopathic scoliosis, it was 21.79 +/- 8.39, 37.44 +/- 11.82, 15.58 +/- 9.91 respectively. And the statistacal study was performed according to scoliosis type, involved segments, curvature degree, and ages. The parameters were very helpful in the evaluation of currigent effect before operation.

Adolescent↗
PubMed1995

Chinese character operating system of traditional Chinese medicine and pharmacology (TCMP).

With the development in research, teaching and literature work in traditional Chinese medicine and pharmacology (TCMP) by means of computers, it has been found that the existing Chinese character operative systems cannot meet the need of carrying out information processing and software development in this field, since these systems do not include many of the common and special terms in TCMP. This makes it inconvenient to exchange academic thoughts in information processing in this field with our colleagues at home and abroad and greatly affects the sharing of the literature data in TCMP. It is therefore necessary to develop a Chinese character operating system applicable to the use of computers in the research of TCMP. Recently, we have developed jointly a Chinese character operating system of TCMP. This system is based on the original GB2312-80 Chinese character international code, to which are added 1,150 Chinese characters commonly used in TCMP. The five-stroke code, which make input possible according to word forms, are used for the input of expanded words. Besides, the system also provides the codes of a number of common names of Chinese materia medica, acupoint names, common terms in traditional Chinese medicine (TCM), TCM disease names, names of classic TCM works, etc. It also provides a convenient character-creating software. We hope that our work will lead to discussions concerning the difficult problems in computer processing of TCMP literature, i.e. the Chinese character.

Database Management Systems↗
PubMed1994

Structural basis for chromosome X-linked agammaglobulinemia: a tyrosine kinase disease.

X-linked agammaglobulinemia (XLA) is a hereditary defect of B-cell differentiation in man caused by deficiency of Bruton tyrosine kinase (BTK). A three-dimensional model for the BTK kinase domain, based on the core structure of cAMP-dependent protein kinase, was used to interpret the structural basis for disease in eight independent point mutations in patients with XLA. As Arg-525 of BTK has been thought to functionally substitute for a critical lysine residue in protein-serine kinases, the mutation Arg-525-->Gln was studied and found to abrogate the tyrosine kinase activity of BTK. All of the eight mutations (Lys-430-->Glu, Arg-520-->Glu, Arg-525-->Gln, Arg-562-->Pro, Ala-582-->Val, Glu-589-->Gly, Gly-594-->Glu, and Gly-613-->Asp) were located on one face of the BTK kinase domain, indicating structural clustering of functionally important residues.

Adenosine Triphosphate↗
PubMed1994

Chemical cross-linking of virion envelope and tegument proteins of herpes simplex virus type 1.

The virion of herpes simplex virus type 1 (HSV-1) consists of three structural components which include the envelope, tegument, and capsid. Little is known about the organization and potential interaction of proteins of the tegument and envelope. In this report, studies with chemical cross-linking reagents were initiated to determine the arrangement of the HSV-1 glycoprotein B (gB) on the viral envelope and its interactions with other virion proteins. With use of four homobifunctional N-hydroxysuccinimide ester reagents, gB was cross-linked to dimers and eventually high molecular weight complexes. In addition, four virion structural proteins were detected to be associated with gB as well as gD and gH but not with gC when cross-linked with dithiobis(succinimidyl propionate). Experimental results indicated that these four proteins are likely to represent viral tegument proteins and one of these proteins was immunologically identified as the known tegument protein, VP16.

Cells, Cultured↗
PubMed1994

Signaling by ATP receptors in astrocytes.

Treatment of primary cultures of rat cerebral cortical astrocytes with extracellular ATP caused a 3- to 4-fold stimulation of mitogen-activated protein (MAP) kinase activity. Studies with agonists and antagonists of P1 and P2 purinergic receptors indicated that this activation is mediated by ATP/P2 purinergic receptors rather than adenosine/P1 purinergic receptors. Increased cAMP levels did not significantly inhibit the activation of MAP kinase by ATP but did inhibit the stimulation of MAP kinase by basic fibroblast growth factor, a polypeptide growth factor that activates the Ras/Raf kinase signaling pathway. These data indicate that ATP/P2 purinergic receptors are coupled to MAP kinase by a signal transduction pathway that is independent of the Raf kinase pathway.

Adenosine Triphosphate↗
PubMed1994

Cloning and sequence analysis of the promoter region of the MRP gene of HL60 cells isolated for resistance to adriamycin.

Non-P-glycoprotein multidrug resistance of HL60/ADR cells appears to be related to overexpression of the MRP gene. Recent studies suggest that this gene may play an important role in a new form of cell resistance to certain chemotherapeutic agents. To examine mechanisms regulating transcriptional activity of this gene, a 2.2-kilobase 5'-flanking sequence of MRP has been isolated from a genomic library prepared from HL60/ADR cells. The 2.2-kilobase DNA fragment linked to the chloramphenicol acetyltransferase (CAT) gene in a reporter plasmid was found to be capable of driving expression of this gene in transient transfection experiments. This DNA containing promoter activity has been sequenced in its entirety and found to contain multiple putative regulatory sites. A series of deletion mutants linked to the CAT reporter gene was used to examine functional domains of the 2.2-kilobase sequence. The results suggest that promoter activity is contained in nucleotides -91 to +103 in a GC-rich region of the MRP genome. Promoter activity contained within this sequence, however, is modulated by both positive and negative regulatory elements. Certain of the regulatory sites contain consensus sequences for positive and negative regulatory elements which have been found in the promoter regions of other genes. Primer extension analysis indicates the presence of multiple major transcriptional start sites from the MRP promoter. Sequence analysis of MRP genomic and complementary DNAs has defined the exon/intron boundaries and the organization of a portion of the 5'-end region of the MRP genome. The results of these studies thus provide new insight in site-specific domains which may function in the regulation of MRP gene expression.

Base Sequence↗
PubMed1994

Deletion within the Src homology domain 3 of Bruton's tyrosine kinase resulting in X-linked agammaglobulinemia (XLA).

The gene responsible for X-linked agammaglobulinemia (XLA) has been recently identified to code for a cytoplasmic tyrosine kinase (Bruton's agammaglobulinemia tyrosine kinase, BTK), required for normal B cell development. BTK, like many other cytoplasmic tyrosine kinases, contains Src homology domains (SH2 and SH3), and catalytic kinase domain. SH3 domains are important for the targeting of signaling molecules to specific subcellular locations. We have identified a family with XLA whose affected members have a point mutation (g-->a) at the 5' splice site of intron 8, resulting in the skipping of coding exon 8 and loss of 21 amino acids forming the COOH-terminal portion of the BTK SH3 domain. The study of three generations within this kinship, using restriction fragment length polymorphism and DNA analysis, allowed identification of the mutant X chromosome responsible for XLA and the carrier status in this family. BTK mRNA was present in normal amounts in Epstein-Barr virus-induced B lymphoblastoid cell lines established from affected family members. Although the SH3 deletion did not alter BTK protein stability and kinase activity of the truncated BTK protein was normal, the affected patients nevertheless have a severe B cell defect characteristic for XLA. The mutant protein was modeled using the normal BTK SH3 domain. The deletion results in loss of two COOH-terminal beta strands containing several residues critical for the formation of the putative SH3 ligand-binding pocket. We predict that, as a result, one or more crucial SH3 binding proteins fail to interact with BTK, interrupting the cytoplasmic signal transduction process required for B cell differentiation.

Adult↗
PubMed1994

Enhanced functional preservation of cold-stored rat heart by a nucleoside transport inhibitor.

This study investigates the hypothesis that inhibition of nucleoside transport during hypothermic storage elevates tissue adenosine (ADO) content and improves the function of the isolated rat heart. The hearts, flushed with a cardioplegic solution containing varying concentrations (0-100 nM) of a nucleoside transport inhibitor, S-(4-nitrobenzyl)-6-thioinosine (NBTI), were immersion-stored at 0 degrees C for 9 hr. Function was assessed after 30 min of working reperfusion. Function of unstored fresh hearts served as controls and poststorage recovery is reported as percentage of control function. Poststorage heart rate in all groups returned to control level after reperfusion. Recovery of other functional parameters in the no-NBTI group was as follows: aortic flow (AF), 56.2 +/- 4.6%; coronary flow (CF), 53.9 +/- 3.2%; cardiac output (CO), 55.5 +/- 4.0%; systolic pressure, 81.6 +/- 2.5%; work, 47.0 +/- 4.2%; and coronary vascular resistance (CVR), 157.1 +/- 7.8% of control. NBTI improved functional recovery in a dose-dependent fashion; the maximal improvement was seen at a dose of 5 nM, in which the recovery was: AF, 78.1 +/- 3.4%; CF, 73.5 +/- 4.4%; CO, 76.7 +/- 3.6%; work, 70.7 +/- 5.0%; and CVR, 127.5 +/- 4.5% of control (P < 0.05 vs. no-NBTI). The ADO A1-receptor antagonist, 1,3-dipropyl-8-cyclopentylxanthine (0.1 microM) blocked the effects of 5 nM NBTI; the recovery of AF, CF, CO, work, and CVR decreased to 62.8 +/- 8.0%, 58.3 +/- 5.0%, 61.5 +/- 3.9%, 54.4 +/- 4.5%, and 163.8 +/- 12.7% of control, respectively (P < 0.05 vs. 5 nM NBTI). Tissue ADO content in 5 nM NBTI hearts at the end of storage was 0.075 +/- 0.025 mumol/g dry wt, which was significantly elevated from 0.016 +/- 0.004 mumol/g dry wt in no-NBTI hearts. Purine release during initial reperfusion was delayed in 5 nM NBTI hearts, indicating the inhibition of nucleoside transport by NBTI. But NBTI treatment did not improve end-storage or end-reperfusion myocardial ATP. In conclusion, the addition of NBTI to cardioplegic solution enhanced tissue ADO and improved poststorage function of the hypothermically stored rat heart. The effect is ADO A1-receptor mediated without invoking energy conservation.

Adenosine↗