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Biomedical subjects

L Qian

Publications and source records attributed to L Qian.

84 records · Page 5Linked to original sources
PubMed1991

Caffeine as a metabolic probe: validation of its use for acetylator phenotyping.

The use of two caffeine metabolite ratios for acetylator phenotyping was validated by demonstrating concordance with two sulfamethazine tests in 178 unrelated healthy subjects. The caffeine metabolites used for this purpose were 5-acetylamino-6-amino-3-methyluracil (AAMU), 1-methylxanthine (1X), and 1-methylurate (1U). The ratio AAMU/(AAMU + 1X + 1U), referred to as molar ratio or N-acetyltransferase, was compared with the ratio AAMU/1X. The results indicated that, for screening purposes, the acetylator phenotype can be determined by analysis of a 6-hour urine sample after a cup of coffee or strong tea or a can of caffeine-containing soft drink. The ratio AAMU/1X is the ratio of choice for the study of subjects in whom variability of xanthine oxidase can be neglected; use of the ratio AAMU/(AAMU + 1X + 1U) appears appropriate for special purposes. Gender, ethnic origin, habitual or moderate consumption of coffee, tea, soft drinks, or ethanol, or cigarette smoking have little if any effect on the caffeine tests for acetylator phenotyping.

Acetylation↗
PubMed1991

Cytogenetic studies on a human rectal carcinoma cell line (HR-8348).

Cytogenetic properties of a human rectal carcinoma cell line (HR-8348) established in China are described. The early (29th passage) and late (93rd passage) passage cells were used for chromosome analysis. HR-8348 was found to have an essentially triploid karyotype. This distribution of chromosome numbers was rather dispersed in early passage, whereas it was concentrated in the 65-70 range in late passage. G-banded karyotype analysis also showed that the numerical distribution of chromosomes was dispersed in early passage and was associated with more abnormal chromosomes. In late passage, the numerical distribution became more stable and the number of abnormal chromosomes was reduced. In 60 metaphases analyzed, 10 marker chromosomes were found. The frequencies of M1, M2 and M3 were 100% in both early and late passage cells. The morphological characteristics of these marker chromosomes and their possible origin and role in the pathogenesis of colorectal carcinoma are discussed.

Chromosome Aberrations↗
PubMed1991

[Determination of cholesterol in natural bezoar by gas chromatography].

A gas chromatographic method for the determination of free and total cholesterol in natural bezoar has been established in this report. The method is simple, specific and accurate. The free and total cholesterol contents in three kinds of bezoar are between 0.072% to 0.214% and 0.546% to 0.608% respectively.

Animals↗
PubMed1983

Determination of linking number of pBR322 DNA.

Do the two chains of the DNA molecule coil round one another plectonemically? If so, the linking number of relaxed circular DNA containing N base pairs, expected from the classical double helix, should be roughly equal to N/10. pBR322 DNA is a covalently closed circular DNA duplex containing 4362 base pairs. When it is in supercoiled state, its linking number calculated from B-DNA should be of the order of 4 X 10(2). We have determined the linking number or relaxed pBR322 DNA I' with electron microcopy. With the help of gel electrophoresis. It is proved that when DNA I' has the writhing number Wr equal 2 + 2, its linking number L equal 1, 2, 3, 4. A further deduction is that the linking number of native pBR322, Lk less than 4362/10. The difference between our experimental results and the estimates from the classical double helix structure is tremendous. The phenomena cannot be explained if there is only one form of DNA structure. Probably the tertiary structure of DNA is intrinsically determined by its primary structure, influenced by various factors such as temperature, pH, solvent, positive ions and the concentration of salt. In fact, right-handed, left-handed and presumably certain intermediate conformations may coexist in the same DNA duplex. In native DNA, the left-handed form is probably not a rare structure and Z-DNA may be only one example of the left-handed family. If the two strands really exist as we described above, it would be convenient for the elucidation of the mechanism of DNA replication and RNA transcription.

DNA, Circular↗
PubMed1982

Isolation of genome-enzyme complex from cytoplasmic polyhedrosis virus of silkworm Bombyx mori.

The genome-enzyme complex is isolated from the silkworm cytoplasmic polyhedrosis virus with DEAE-Sephadex column chromatography after ultraviolet irradiation. The genome-enzyme complex shows both RNA-polymerase and methyltransferase activities while using 3H-UTP and [3H-methyl]-S-adenosyle-L-methionine as substrates. Like the double-stranded RNA genome of CPV, the genome-enzyme complex could be separated into nine segments on polyacrylamide gel electrophoresis. It is demonstrated that the RNA polymerase and methyl-transferase are tightly bound to the double-stranded RNA genome and that the individual segments of the genome-enzyme complex all possess RNA-polymerase and methyltransferase activities. It appears that each segment of the double-stranded RNA genome is transcribed independently.

Bombyx↗
PubMedDate not supplied

Early organ-specific hemorrhage-induced increases in tissue cytokine content: associated neurohormonal and opioid alterations.

Hemorrhage is associated with an impairment in the immune response and with increased concentrations of circulating inflammatory cytokines. The present study determined the time course and localization of alterations in circulating and tissue pro-inflammatory cytokines (TNF-alpha, IL-1-alpha and -beta) in response to fixed-pressure (40 mm Hg) hemorrhage as well as the associated hanges in circulating neurohormonal and opioid mediators. Conscious unrestrained non-heparinized male Sprague-Dawley rats (n = 24) underwent hemorrhage followed by standard resuscitation with lactated Ringer's solution. Animals were sacrificed at three time points; immediately after the hemorrhage period, at completion of resuscitation and 1.5 h after the resuscitation period. Hemorrhage resulted in marked elevations in circulating levels of TNF-alpha, which averaged 860 +/- 201 pg/ml. The levels were similarly elevated following fluid resuscitation (877 +/- 196 pg/ml) and had decreased towards baseline 1.5 h after completion of resuscitation (281 +/- 134 pg/ml). TNF-alpha was not detectable in plasma of time-matched controls. Hemorrhage elevated TNF-alpha content in spleen (25%), lung (55%) and heart (20%), and tissue content remained elevated despite resuscitation. No significant changes in tissue content of TNF-alpha were detected in the liver, kidney or brain. Circulating levels of IL1-alpha and -beta were not detectable in either the time-matched controls or hemorrhaged animals. However, statistically significant elevations in tissue content of IL-1 alpha were observed in heart, spleen, lung, gut and whole brain (15-30%). Tissue content of IL-1 beta did not change in response to hemorrhage and/or fluid resuscitation. Activation of sympathetic outflow, as evidenced by a 3- to 4-fold elevation in circulating epinephrine and norepinephrine levels, was observed immediately after hemorrhage, and was associated with a 5-fold rise in circulating beta-endorphin. These results demonstrate an early increase in tissue cytokine content following hemorrhagic shock, which is associated with elevations in circulating catecholamines and endogenous opioids, consistent with their potential modulatory role in this response.

Animals↗
PubMedDate not supplied

Alteration of mRNA transcript levels of rat testicular cells following procarbazine administration.

The present study examined the effects of a single 400-mg/kg dose of procarbazine upon various testicular mRNA transcript levels in adult Sprague-Dawley rats. Northern blot hybridization was employed to measure the steady-state mRNA levels of proteins specific for Sertoli cells (adrogen-binding protein [ABP] and transferrin) and spermatids (protamine 1 and transitional protein 2). In addition, mRNA transcript levels were determined for germ cell-specific hemiferrin and insulin-like growth factor-1 (IGF-1), which in adult rats is present predominantly in primary spermatocytes. Furthermore, the chronology of the effects of procarbazine upon spermatogonial populations was examined in whole mounts of seminiferous tubules. The effect of procarbazine upon spermatogenesis was first noted among mature A3, young A4, and B spermatogonia 48-72 hours after drug administration. These results indicate that A2 through intermediate spermatogonia were most susceptible to procarbazine. In addition, degeneration of spermatocytes and young spermatids was evident by 5 days. Northern blot analysis of testicular poly (A)+ RNA revealed that the steady-state levels of mRNA transcripts of the spermatid nuclear proteins (protamine 1, 700 bp; and transitional protein 2, 580 bp) remained relatively unchanged for 5 days after procarbazine administration but were significantly decreased by more than 70% by 7 days. On the other hand, the steady-state mRNA levels for the Sertoli cell proteins ABP (1.7 kb) and transferrin (2.7 kb) were decreased by 45% and 50% (P < 0.05), respectively, 2 days after procarbazine administration. Significant suppression of ABP mRNA levels persisted through day 5, with partial recovery noted on day 7.(ABSTRACT TRUNCATED AT 250 WORDS)

Androgen-Binding Protein↗