Search PubMed⌕ Search

Biomedical subjects

C Ma

Publications and source records attributed to C Ma.

At least 181 records · Page 10Linked to original sources
PubMed1992

[Influence of 5.7-dihydroxytryptamine on electro-acupuncture analgesia and substance P level in central nervous system of the arthralgic rats].

The relation between electroacupuncture (EA) analgesia (A) and substance P (SP) level in the brain stem (BS) and lumbar spinal cord (LSC) of arthralgic rats was investigated. The rats were divided into three groups: 1)5.7-dihydroxytryptamine (5.7-DHT) + EA, 2) vehicle (V) + EA, and 3)5.7-DHT. All the animals were induced arthralgesia by injecting Freund's adjuvant 7 days after cisterna injection of 5.7-DHT or vehicle. The SP level in the BS and LSC was determined by RIA. The results indicated that in V + EA group the EA could prolong tail flick latency by 39.6%, but in other two groups did not. The SP level in LSC of V + EA group (179.1 +/- 11.5 pmol/g) was higher than that in the 5.7-DHT + EA (135.9 +/- 9.3pmol/g) and 5.7-DHT (125.8 +/- 10.0 pmol/g) groups. It suggested that both EA and arthralgia could activate the descending 5-HTergic inhibitory system to inhibit the release of SP in LSC. When the 5-HTergic system was destroyed by 5.7-DHT, the EAA was attenuated, and the SP level in LSC was lowered due to its release was decreased by EA and arthralgia.

Acupuncture Analgesia↗
PubMed1992

[Studies on the TLC scanning determination of lignans in Diphylleia sinensis Li].

A simple, sensitive and accurate method for the separation and determination of the lignans: podophylltoxone (I), isopicropodophyllone (II), picropodophyllone (III), dehydropodophyllotoxin (IV), picropodophyllin (V), podophyllotoxin (VI), 4'-demethylpodophyllotoxin (VII) and diphyllin (VIII) is described. The sample solution was applied at a point 1 cm from the bottom edge of the HPTLC silica gel plate (10 cm x 10 cm), dichloromethane-diethyl ether (4:1) was used as the developing solvent. The plate was saturated for 30 min and then developed twice for 9.5 cm using ascending technique. The plate was sprayed with 2.5% ammonium ceric sulphate--20% nitric acid and toasted for 15 min at 120 degrees C, then fumigated with ammonia solution for 20 min at room temperature to intensify the spot color. The spots were scanned with a Shimadzu CS-930 TLC scanner. The contents of eight lignans in Diphylleia sinensis was calculated by comparison with standards spotted on the same plate. The standard curves were linear in the range of 0.48-2.52 micrograms for the eight lignans. The method has been applied to the analysis of various samples and can be used for the quality control of Diphylleia sinensis, podophyllum and dysosma preparations used in clinic.

Chromatography, Thin Layer↗
PubMed1992

[Changes in lymphocyte beta-receptor density in patients with heart failure before and after metoprolol or captopril administration].

Human lymphocyte beta-receptor density in heart diseases with various degrees of heart function of 41 cases was determined. beta-receptor density and ejection fraction in congestive heart failure (CHF) before and after conventional therapy with small dose of beta-blocker (metoprolol) or captopril were compared. The aim was to clarify the action and safety of beta-blocker in the treatment of CHF. The results revealed that there was no statistical difference between beta-receptor density in CHF with cardiac function of degree I and II (516.57 +/- 85.93 fmol/10(7) cells, mean +/- s) and in normal controls (576.56 +/- 97.18 fmol/10(7) cells, P > 0.05), while beta-receptor density in CHF of degree III and IV was much lower than that in normal controls (decreased by 50%). There was no statistical difference of beta-receptor density between rheumatic heart disease and cardiomyopathy. Metoprolol up-regulated beta-receptor density from 302.40 +/- 100.91 to 459.60 +/- 174.34 fmol/10(7) cells (P < 0.05), but no change was observed after treatment by captopril. Ejection fraction was increased in both groups (P < 0.01). The results revealed that beta-receptor density was decreased in certain kinds of CHF but no relationship was observed between CHF of different etiology. beta-receptor density was up-regulated by beta-blocker, thus it indicates that it is rational to use beta-blocker for the treatment of certain kinds of CHF. And the use of small dose of beta-blocker with conventional therapy of heart failure might reduce the negative inotropic action of the former.

Adult↗
PubMed1991

Acute effects of oral pyridostigmine bromide on conditioned operant performance in rats.

Pyridostigmine bromide (Pyr), the current drug of choice in the management of myasthenia gravis, has been suggested for use in Alzheimer's dementia, and as a prophylactic treatment for intoxication with organophosphate cholinesterase inhibitors. The present study was undertaken to evaluate the dose-response and time-course effects of acute oral administration of Pyr over a broad dose range (3-40 mg/kg) on the lever pressing of rats maintained under a multiple fixed-ratio (FR-20) time-out schedule of reinforcement for water reward. The drug produced a dose-dependent biphasic response depression in the overall rate of FR responding. Low doses of Pyr (less than or equal to 12 mg/kg) that caused no gross signs of toxicity only moderately decreased rates of responding, primarily due to a decrease in response rates. Whereas high doses of Pyr (greater than 24 mg/kg) which produced overt signs of peripheral cholinergic intoxication markedly suppressed overall responding, primarily due to cessation of responding. The lowest effective dose of performance disruption was 6 mg/kg, and the ED50 was calculated as 23.3 (17.9-28.7) mg/kg. The time-course data of performance disruption showed that low doses of Pyr (less than or equal to 12 mg/kg) had an onset latency within 40-80 min and a duration of 20-80 min, whereas high doses (greater than or equal to 24 mg/kg) had an onset latency of 20-40 min and a duration greater than 80 min. These results suggest the recommended human therapeutic or prophylactic regimen of 30-120.mg Pyr, orally taken each 8 hours, might adversely affect behavioral performance.

Administration, Oral↗
PubMed1991

Origins of replication: timing and chromosomal position.

Several new methods have been used to localize replication initiation sites in mammalian chromosomes. The results of these studies argue strongly for the presence of defined sequence elements that function much like the origins in the genomes of simple microorganisms. However, relatively disparate results from in vivo and in vitro studies suggest that initiation reactions in mammalian chromosomes may have unique features, possibly related to a more complicated chromosomal architecture.

Animals↗
PubMed1991

Combined localized current field hyperthermia and irradiation for intraocular tumors.

Ten patients with large melanomas and one patient with recurrent retinoblastoma were treated with combined localized current field (LCF) hyperthermia and iodine 125 irradiation delivered by episcleral plaque. Tumors were heated to 43 degrees to 45 degrees C for 28 to 45 minutes. Localized current field hyperthermia when combined with irradiation appeared to induce rapid tumor necrosis. One eye enucleated 17 hours after treatment showed only focal necrosis of the melanoma, while another eye demonstrated extensive necrosis 60 hours after treatment. In all remaining eyes, tumor regression occurred within the first month of treatment. Complications included cataract formation in six eyes, hemorrhagic retinal detachment in five eyes, and phthisis in two eyes. Complications from combined therapy of large intraocular tumors in this series appeared to result from the rapid necrosis of the tumor and secondary intraocular inflammation. Intraocular temperature dosimetry measurements demonstrated a temperature gradient of not more than -0.23 degrees C/mm-1 per axial millimeter from the episcleral plaque surface to the apex of the tumor. The authors believe that LCF hyperthermia could be a suitable means of application of hyperthermia in patients with intraocular tumors if further modifications were performed to reduce ocular complications.

Brachytherapy↗
PubMed1991

[Preliminary investigation of liver alveolar echinococcosis and liver cystic, echinococcosis in Xiji County, Ningxia].

This article reports on the result of an investigation on the prevalence of liver alveolar echinococcosis (LAE) and liver cystic echinococcosis (LCE) in the peasants and the residents of Xiji County, Ningxia Hui Autonomous Region. Among 2,389 selected persons examined with B-ultrasound, 197 cases were diagnosed to have LAE or LCE; the prevalence being 8.2%. Of the 197 cases, 141 (5.9%) had LAE; 56 (2.3%) had LCE. Among 1,413 peasants, 9.7% had LAE; 3.8% had LCE. Among 976 residents, 0.4% had LAE, 0.2% had LCE. Obviously, the peasants were more prone to be infected with the disease, suggesting LAE had much to do with the job of hunting the fox and capturing the Citellus dauricus, while the infectious source of LCE was mainly the domestic dog.

Adolescent↗
PubMed1990

The IS10 antisense RNA blocks ribosome binding at the transposase translation initiation site.

Transposase (tnp) expression from insertion sequence IS10 is controlled, in part, by an antisense RNA, RNA-OUT, which pairs to the translation initiation region of the tnp mRNA, RNA-IN. Genetic experiments suggest that control occurs post-transcriptionally. Here, we present evidence that bears on the control mechanism. Specific ribosome binding at the tnp translation initiation site is demonstrated in vitro. Two mutations that alter tnp translation in vivo are shown to have corresponding effects in vitro. Most importantly, RNA-OUT/RNA-IN pairing is shown to block ribosome binding. In conjunction with the work described in the accompanying paper, we propose that inhibition of ribosome binding also occurs in vivo, and that it is sufficient to account for control. Implications for translational control in analogous systems are discussed.

Base Sequence↗
PubMed1990

Multiple origins of replication in the dihydrofolate reductase amplicons of a methotrexate-resistant chinese hamster cell line.

We recently showed that replication initiates in the early S period at two closely spaced zones in the 240-kilobase (kb) dihydrofolate reductase (DHFR) amplicon of the methotrexate-resistant Chinese hamster ovary cell line CHOC 400. Both of these initiation loci (ori-beta and ori-gamma) have previously been cloned in a recombinant cosmid. In this study, we identified a third early-firing initiation locus (ori-alpha) in the much larger DHFR amplicon of the independently isolated methotrexate-resistant Chinese hamster cell line DC3F-A3/4K (A3/4K). We describe the molecular cloning of this newly identified locus and demonstrate by chromosomal walking that ori-alpha lies approximately 240 kb upstream from ori-beta. Using overlapping cosmid clones for more than 450 kb of DNA sequence from this region of the DHFR domain, we have monitored the replication pattern of the amplicons in synchronized A3/4K cells. These studies suggest that ori-alpha, ori-beta, and ori-gamma are the only early-firing initiation sites in this 450-kb sequence. In addition, we have been able to roughly localize the termini between ori-alpha and ori-beta and between ori-alpha and the next origin in the 5' direction. Thus, we have now isolated the equivalent of three early-firing replicons (including their origins) from a well-characterized chromosomal domain. With these tools, it should be possible to determine those properties that are shared by the origins and termini of different replicons and which are therefore likely to be functionally significant.

Animals↗