Biomedical subjects

C Xiao

Publications and source records attributed to C Xiao.

85 records · Page 5Linked to original sources

PubMed1995

[A survey on distribution of red cell blood group systems in naxi and primi ethnic groups].

A survey of distribution of red cell blood group systems, including ABO, MNSs, Rh and P, was carried out on the Naxi and Primi ethnic groups in Yunnan province. The results based on 104 cases in each of the two ethnic groups showed that both Naxi and Primi possessed a high gene frequency r of 0.6082 and 0.6882, respectively, with gene frequency p = q. The gene frequency m of Naxi (0.8509) was found to be very high among the populations studied in China until now, only next to that of Lizu (0.8709). The most common phenotype of Rh system was CcDE- in both Naxi and Primi, with a quite high cDE frequency. No case of Rh negative was observed in the two ethnic groups. The P1 in Naxi approximated to that in Primi. The red cell blood group systems and their genetic distances suggested that the Naxi and Primi was genetically close to ethnic groups of North China, but different from those of South China. This fact suggests that these two ethnics groups originated from the North China.

ABO Blood-Group System↗

PubMed1994

Distribution of red cell blood group systems in Achang and De'ang ethnic groups in China.

A survey on the distribution of red cell group systems, including ABO, MNSs, Rhesus and P, was carried out in the Achang and De'ang ethnic groups in Yunnan Province, South-West China. The Achangs are characterized by the highest frequency of IA in China, while the De'angs show a high frequency of IO and CDe. The distribution of these blood group systems in Achang and De'ang exhibits the same characteristics observed in other ethnic groups of South China.

ABO Blood-Group System↗

PubMed1994

High density cultivation of a recombinant CD-1 cell line producing prourokinase using a Biosilon microcarrier culture system.

CD-1, a genetically-engineered CHO cell line, was cultivated with a Biosilon microcarrier culture system. We successfully cultivated CD-1 cells to a very high density (over 1 x 10(7) cells/ml). Prourokinase was stably secreted at about 180 IU/10(6) cells/24 h. Experiments showed that CD-1 cells growing on Biosilon microcarriers were able to spontaneously release from the microcarriers, then reattach and proliferate on fresh microcarriers. This makes it very easy to scale up production. The microcarriers could be reused several times without affecting adhesion, proliferation and prourokinase secretion. With CM-PECC membrane radial flow chromatography and MPG chromatography, the prourokinase in conditioned medium could be purified to a specific activity of 1 x 10(5) IU/mg of protein. The purification factor was about 600 fold, and approximately 90% of the biological activity was recovered.

Animals↗

PubMed1994

High density cultivation of genetically-engineered CHO cell lines with microcarrier culture systems.

Genetically-engineered CHO cell lines, r beta-13 and CLF-8B2, were cultivated with the MC-1 microcarrier culture system. The cell density could be enhanced by increasing the concentration of microcarrier. At a microcarrier concentration of 10 mg/ml, the cell density could reach 4 to 5 x 10(6) cells/ml. It was shown that these cell lines would spontaneously release from the microcarrier to attach to and proliferate on fresh microcarriers. We were thus able to scale up cultivation using a simple method, i.e. by adding fresh microcarriers and medium directly into the culture system to about 2, 4 or 8 times the original volume. Using a perfusion culture system, we have successfully cultivated CLF-8B2 cells in a 2 L bioreactor for several weeks at medium perfusion rates of 0.5 to 3 working volumes. Prourokinase was stably secreted.

Animals↗

PubMed1994

[New species of Haloarcula].

Three strains of pleomorphic halobacteria (A5, B2 and B-B2) were isolated from salt lakes of Xinjiang, China. Based on the Bergey's Manual of Systematic Bacteriology, Volume 3 (1989) and the analytical results of polar lipids, the three strains could be included in the genus Haloarcula. But since they differ from normally accepted two species of this genus in cell shape and physiological and biochemical features, it is suggested that the three strains belong to a new species, called Haloarcu la aidinensis sp. nov.

China↗

PubMed1992

Pilot production of high-titer interferon and virus with a microcarrier suspension culture system.

We have successfully cultured four cell lines--L929, BHK-13, BHK-21 and CHO-K1 using an MC-1 type microcarrier made in our academy. With the microcarrier in a concentration of 5 mg/ml, the cell density was about 30 x 10(4) cells/ml; after 3 days in suspension culture, the cells could proliferate to 1 x 10(6) cells/ml. At this time, when L929 cells were primed with 25 IU/ml MuIFN for 14-24 h and then superinduced with NDV, cycloheximide (20 micrograms/ml) and actinomycin D (2 micrograms/ml), the titer of IFN reached approximately 10(5) IU/ml (10(5) IU/mg of protein, expressed in specific activity). When VSV was inoculated into the other three cell line cultures, the viral titer reached 6 Log TCID50/ml or much higher. The yield with the CHO-K1 cell line was the highest, reaching titers of 7-8 Log TCID50/ml. These titers were similar to those seen in stationary culture. With trypsin-citrate solution and a more rapid stirring speed, the cells could be satisfactorily released from the microcarriers and reattached on fresh ones. These experiments show that the microcarrier suspension culture system is suitable for producing large scale, high-titer, low-cost vaccines and IFNs, both natural and recombinant, using genetically-engineered CHO cell lines.

Animals↗

PubMed1992

[The characterization of mutant No. 68 from midecamycin producing strain S. mycarofaciens 1748].

A stable mutant No. 68 was obtained by treatment of S. mycarofaciens 1748 spores at high temperature. The electromicroscopic examination has shown that the mutant No. 68 and parent strain 1748 both have the spore chains of the spiratype. The spores of both strain are cylindrical in shape. The only difference is that the spores of the mutant No. 68 are of smooth surface, but the 1748 are of thorny. The physiological characteristics of both strains are also very similar with slight differences in utilization of few carbon sources and in cultural characters in few medium. Feeding experiment has shown that the mutant No. 68 was blocked in the formation of the macrolide lactone in the midecamycin biosynthetic pathway. This suggested that the mutant No. 68 might be a polyketide synthase genes deficient mutant. The ability of the mutant No. 68 to convert spiramycin into 4"-propionylspiramycin indicated that the mutant No. 68 contained the midecamycin 4"-propionyltransferase and could be used for microbial bioconversion of spiramycin into 4"-propionylspiramycin.

Leucomycins↗

PubMed1989

Optical measurement of action potential activity in invertebrate ganglia.

Optical monitoring methods have reached the level of development where activity from a network of cells can be recorded in a minimally-dissected behaving animal. The spike activity in the buccal ganglion of Navanax was monitored during feeding and activity in the Aplysia abdominal ganglion was monitored during the gill-withdrawal reflex. Approximately 30 neurons in the Navanax buccal ganglion were active during feeding and between 250 and 400 neurons in the Aplysia abdominal ganglion were active during the gill-withdrawal reflex. A reasonably complete understanding of the neuronal basis of the gill withdrawal may not be possible with presently available scientific methods. Substantial improvements in signal-to-noise ratio in optical measurements will be necessary before the majority of synaptic potentials can be detected optically. Understanding circuits that involve more than a few neurons will be a challenge to neurobiologists.

Action Potentials↗

PubMed1988

Optical monitoring of activity of many neurons in invertebrate ganglia during behaviors.

Optical methods for monitoring neuron activity were developed because these methods lend themselves to simultaneous multiple-site measurements. With the use of new voltage-sensitive dyes, the dye-related pharmacology and photodynamic damage appear to be relatively unimportant. Using multiple-site measurements made with a 124-element photodiode array, we estimated that approximately 30 of the 200 neurons present in the Navanax buccal ganglion make action potentials during feeding and that approximately 300 of the 1100 neurons present in the Aplysia abdominal ganglion are active during the gill-withdrawal reflex. The fact that a light mechanical touch to the siphon skin activated such a large number of neurons in the abdominal ganglion suggests that understanding the neuronal basis of the gill-withdrawal reflex and its behavioral plasticity may be forbiddingly difficult.

Animals↗

PubMedDate not supplied

Anti-inflammatory and anti-oxidative effects of cherries on Freund's adjuvant-induced arthritis in rats.

OBJECTIVES: To investigate the anti-inflammatory and anti-oxidative effects of anthocyanins from cherries on Freund's adjuvant-induced arthritis (AIA) in rats. METHODS: Arthritis was induced intradermally by injection with 0.1 mL of complete Freund's adjuvant (CFA) into the right hind footpad of male Sprague Dawley (SD) rats. Anthocyanins at 40, 20 and 10 mg/kg (body weight) were administered orally to the treated rats for 28 days after the injection. Tumour necrosis factor-alpha (TNFalpha) in serum and prostaglandin E2 (PGE2) in paws were assayed by radioimmunoassay (RIA), and anti-oxidative effects was assayed by measuring total anti-oxidative capacity (T-AOC), superoxide dismutase (SOD) and malondialdehyde (MDA) in serum. RESULTS: Anthocyanins at 40 mg/kg significantly decreased the levels of TNFalpha in serum and PGE2 in paws, simultaneously improving the anti-oxidative status of AIA. We found that at this dosage T-AOC was potentized, the activity of SOD increased and the level of MDA in serum decreased. However, anthocyanins at 20 and 10 mg/kg had less effect on the inflammatory factors and anti-oxidative capacity of AIA. CONCLUSIONS: Anthocyanins have potential anti-inflammatory and anti-oxidative effects on AIA.

Animals↗

PubMedDate not supplied

Mitochondrial polymorphisms as risk factors for endometrial cancer in southwest China.

It is just in recent years that mitochondrial DNA (mtDNA) mutations have been found in solid tumors. Although a direct link between the presence of mtDNA mutations and the development of tumors has not been made, mtDNA mutations might prove significant in the detection of tumor recurrence and possibly in the detection of genotoxic damage. To investigate the relationship between mtDNA variation and endometrial cancer, we collected blood samples from subjects with Han native background in Yunnan province in China, 49 of them with pathologically conformed endometrial cancer and 31 as controls with no cancer disease and sequenced two hypervariable segments of control region, part of 16sRNA gene, tRNA(leu) (tRNA is transfer RNA) gene and ND1 gene of mtDNA and identified some diagnostic polymorphisms by restriction fragment length polymorphism of coding region of mtDNA. We could not identify the suspected mutations that are related to diabetes and obesity from our endometrial cancer patients. However, our data showed that patients with endometrial cancers clustered in haplogroup D in a significantly higher frequency when compared with controls, implicating a possible association of haplogroup D to endometrial cancer. We concluded that mitochondrial polymorphisms in haplogroup D might play a genetic role in predisposing to endometrial cancer.

Case-Control Studies↗

PubMedDate not supplied

Molecular characterization of myxozoan parasites from Lake Sasajewun, Algonquin Park, Ontario, by riboprinting.

The small subunit-rRNA genes of 18 myxozoans from Lake Sasajewun, Algonquin Park were amplified and digested with restriction endonucleases for riboprinting analysis. Identical riboprints were not found between the myxosporeans and the actinosporeans. The distinct riboprinting patterns observed among these myxozoans indicate considerable genetic diversity within this group. Identical riboprints were found between Myxobolus pendula and Myxobolus pellicides, and between triactinomyxon 'C' and Triactinomyxon ignotum. Parsimony analysis of the riboprints demonstrated that neither the myxosporeans nor the actinosporeans formed a monophyletic group. Some species of Myxobolus are more closely related to forms of triactinomyxon, echinactinomyxon or raabeia than to other Myxobolus species. These results are consistent with the two-host life cycle hypothesis of myxozoans that myxosporeans and actinosporeans are alternating stages of the same organisms.

Animals↗

PubMedDate not supplied

Recent advances in our knowledge of the Myxozoa.

In the last few years two factors have helped to significantly advance our understanding of the Myxozoa. First, the phenomenal increase in fin fish aquaculture in the 1990s has lead to the increased importance of these parasites; in turn this has lead to intensified research efforts, which have increased knowledge of the development, diagnosis. and pathogenesis of myxozoans. The hallmark discovery in the 1980s that the life cycle of Myxobolus cerebralis requires development of an actinosporean stage in the oligochaete. Tubifex tubifex, led to the elucidation of the life cycles of several other myxozoans. Also, the life cycle and taxonomy of the enigmatic PKX myxozoan has been resolved: it is the alternate stage of the unusual myxozoan, Tetracapsula bryosalmonae, from bryozoans. The 18S rDNA gene of many species has been sequenced, and here we add 22 new sequences to the data set. Phylogenetic analyses using all these sequences indicate that: 1) the Myxozoa are closely related to Cnidaria (also supported by morphological data); 2) marine taxa at the genus level branch separately from genera that usually infect freshwater fishes; 3) taxa cluster more by development and tissue location than by spore morphology; 4) the tetracapsulids branched off early in myxozoan evolution, perhaps reflected by their having bryozoan, rather than annelid hosts; 5) the morphology of actinosporeans offers little information for determining their myxosporean counterparts (assuming that they exist); and 6) the marine actinosporeans from Australia appear to form a clade within the platysporinid myxosporeans. Ribosomal DNA sequences have also enabled development of diagnostic tests for myxozoans. PCR and in situ hybridisation tests based on rDNA sequences have been developed for Myxobolus cerebralis, Ceratomyxa shasta, Kudoa spp., and Tetracapsula bryosalmonae (PKX). Lectin-based and antibody tests have also been developed for certain myxozoans, such as PKX and C. shasta. We also review important diseases caused by myxozoans, which are emerging or re-emerging. Epizootics of whirling disease in wild rainbow trout (Oncorhynchus mykiss) have recently been reported throughout the Rocky Mountain states of the USA. With a dramatic increase in aquaculture of fishes using marine netpens, several marine myxozoans have been recognized or elevated in status as pathological agents. Kudoa thyrsites infections have caused severe post-harvest myoliquefaction in pen-reared Atlantic salmon (Salmo salar), and Ceratomyxa spp., Sphaerospora spp., and Myxidium leei cause disease in pen-reared sea bass (Dicentrarchus labrax) and sea bream species (family Sparidae) in Mediterranean countries.

Animals↗