Biomedical subjects

Y Cai

Publications and source records attributed to Y Cai.

At least 127 records · Page 7Linked to original sources

PubMed1999

Metabolic fate of oxidized guanine ribonucleotides in mammalian cells.

8-Oxo-7,8-dihydroguanine- (8-oxoguanine-) containing nucleotides are generated in the cellular nucleotide pool by the action of oxygen radicals produced during normal cellular metabolism. We examined the interconversion and metabolic fate of 8-oxoguanine-containing ribonucleotides in mammalian cells. (1) 8-OxoGTP can be generated not only by direct oxidation of GTP but also by phosphorylation of 8-oxoGDP by nucleotide diphosphate kinase, and the 8-oxoGTP thus formed can serve as a substrate for RNA polymerase II to induce transcription errors. (2) MTH1 protein carrying intrinsic 8-oxo-dGTPase activity has the potential to hydrolyze 8-oxoGTP to 8-oxoGMP, thus preventing misincorporation of 8-oxoguanine into RNA. 8-OxoGMP, the degradation product, cannot be reutilized, since guanylate kinase, which has the potential to phosphorylate both GMP and dGMP, is inactive on 8-oxoGMP. (3) Ribonucleotide reductase, which catalyzes reduction of four naturally occurring ribonucleoside diphosphates, cannot convert 8-oxoguanine-containing ribonucleotide to the deoxyribonucleotide. This step appears to serve as a gatekeeper to prevent formation of mutagenic substrates for DNA synthesis from oxidized ribonucleotides.

Animals↗

PubMed1999

The distribution of zinc selenite and expression of metallothionein-III mRNA in the spinal cord and dorsal root ganglia of the rat suggest a role for zinc in sensory transmission.

Zinc appears to play a role in synaptic transmission in the hippocampus. We tested the hypothesis that zinc is similarly involved in sensory transmission by determining whether vesicular zinc and metallothionein-III (MT-III), a zinc-binding protein, are localized in rat primary afferent neurons. MT-III mRNA, measured using RT-PCR, and MT-III immunoreactivity, were both present in the spinal cord as well as the thoracic and lumbar dorsal root ganglia (DRG). At a time (24 hr) that allows retrograde transport of zinc selenite to cell bodies, only small-diameter neurons and neurons scattered throughout lamina V of the spinal cord were stained by sodium selenite injected intrathecally. This stain disappeared if a ligature was placed on the dorsal root to block axonal transport, demonstrating that these cells are, in fact, zinc-containing primary afferent neurons. When assessed 1 hr after sodium selenite, stain was distributed throughout the neuropil of the spinal cord, especially in lamina III and the area surrounding the central canal. Even in rhizotomized animals, large- and small-diameter DRG neuronal cell bodies were also stained with either selenite (1 hr) or 6-methoxy 8-para-toluene sulfonamide quinoline (TSQ). Paradoxically, this unique pool of zinc was eliminated in large-diameter DRG neurons after neonatal capsaicin treatment, which had no effect on selenite stain or MT-III mRNA content in small-diameter DRG neurons. In summary, we demonstrate that there is a population of capsaicin-insensitive small-diameter primary afferent neurons that are zinc-containing. In addition, there is a unique pool of capsaicin-sensitive zinc that is associated with large-diameter cell bodies.

Animals↗

PubMed1999

Mutations in autosomal dominant polycystic kidney disease 2 gene: Reduced expression of PKD2 protein in lymphoblastoid cells.

The polycystic kidney disease 2 (PKD2) gene, encoding a 968-amino acid integral membrane protein with six predicted membrane-spanning domains and intracellular NH2 and COOH termini, is mutated in approximately 15% of the cases of autosomal dominant polycystic kidney disease (ADPKD), a common genetic disease frequently resulting in renal failure. For a better understanding of the cause of this disorder, we searched for mutations in the PKD2 gene in two PKD2-linked families characterized by different clinical phenotypes. A common polymorphism, a nonsense mutation, and a frameshift mutation were found. Both mutations are predicted to produce truncated proteins of 314 and 386 amino acids, arrested at the first extracellular loop of the protein. Restriction enzyme analysis of polymerase chain reaction (PCR) and reverse transcriptase (RT)-PCR products, respectively, showed that mutations cosegregated with the disease and mutated alleles were expressed at the messenger RNA level in lymphoblastoid cell lines. However, in these cells, Western blot analysis showed only PKD2 normal protein, and it was expressed at a lower level than that found in cells without the PKD2 mutation. These findings suggest that in lymphoblastoid cells, the truncated protein product of the mutant allele may not be stable.

Aged↗

PubMed1999

Lactobacillus paralimentarius sp. nov., isolated from sourdough.

Six strains of lactic acid bacteria isolated from sourdough were characterized taxonomically. They were Gram-positive, catalase-negative, facultatively anaerobic rods that did not produce gas from glucose. Morphological and physiological data indicated that the strains belong to the genus Lactobacillus and they were similar to Lactobacillus alimentarius in phenotypic characteristics. These strains shared the same phenotypic characteristics and exhibited intragroup DNA homology values of over 89.8%, indicating that they comprised a single species. The G + C content of the DNA for the strains was 37.2-38.0 mol%. The 16S rRNA sequence of representative strain TB 1T was determined and aligned with that of other Lactobacillus species. This strain was placed in the genus Lactobacillus on the basis of phylogenetic analysis. L. alimentarius was the most closely related species in the phylogenetic tree and this species also showed the highest sequence homology value (96%) with strain TB 1T. DNA-DNA hybridization indicated that strain TB 1T did not belong to L. alimentarius. It is proposed that these strains are placed in the genus Lactobacillus as a new species, Lactobacillus paralimentarius sp. nov. The type strain of L. paralimentarius is TB 1T, which has been deposited in the Japan Collection of Microorganisms (JCM) as strain JCM 10415T.

Bacterial Typing Techniques↗

PubMed1999

Conservation of putative promoter sequences located upstream of chlamydial major sigma factor gene, sigA among Chlamydia spp.

A highly conserved 40-nucleotide sequence was identified. Two completely conserved sequences, TAGATT and TAAACT, separated by 17 nucleotides resemble the consensus sequence recognized by the Escherichia coli major sigma factor and sequence found in other chlamydial promoters. In addition, the adenine-rich sequence present in many chlamydial promoters was also conserved upstream of the putative -35 element. These findings suggest that the conserved sequence may play a role in the regulatory function at the transcriptional level. Multiple ATG codons were found at the 5'-terminal region of the chlamydial sigA ORFs except for Chlamydia pneumoniae, although the putative Shine-Dargarno sequence was absent.

Bacterial Outer Membrane Proteins↗

PubMed1999

Characterization and identification of Pediococcus species isolated from forage crops and their application for silage preparation.

Pediococcus species isolated from forage crops were characterized, and their application to silage preparation was studied. Most isolates were distributed on forage crops at low frequency. These isolates could be divided into three (A, B, and C) groups by their sugar fermentation patterns. Strains LA 3, LA 35, and LS 5 are representative isolates from groups A, B, and C, respectively. Strains LA 3 and LA 35 had intragroup DNA homology values above 93.6%, showing that they belong to the species Pediococcus acidilactici. Strain LS 5 belonged to Pediococcus pentosaceus on the basis of DNA-DNA relatedness. All three of these strains and strain SL 1 (Lactobacillus casei, isolated from a commercial inoculant) were used as additives to alfalfa and Italian ryegrass silage preparation at two temperatures (25 and 48 degrees C). When stored at 25 degrees C, all of the inoculated silages were well preserved and exhibited significantly (P < 0.05) reduced fermentation losses compared to that of their control in alfalfa and Italian ryegrass silages. When stored at 48 degrees C, silages inoculated with strains LA 3 and LA 35 were also well preserved, with a significantly (P < 0.05) lower pH, butyric acid and ammonia-nitrogen content, gas production, and dry matter loss and significantly (P < 0.05) higher lactate content than the control, but silages inoculated with LS 5 and SL 1 were of poor quality. P. acidilactici LA 3 and LA 35 are considered suitable as potential silage inoculants.

Colony Count, Microbial↗

PubMed1999

Polycystin-2 expression is developmentally regulated.

PKD2 encodes a protein of unknown function that is mutated in 15% of autosomal dominant polycystic kidney disease (ADPKD) families. We used polyclonal antisera against PKD2 to examine the pattern of Pkd2 expression in staged mouse embryos. Staining for Pkd2 was documented as early as the 6th embryonic day (day E6) in the embryonic ectoderm and endoderm. Low-intensity staining is seen in metanephric ureteric bud at day E12.5. By day E15.5, the adult pattern of expression is established with low level staining in proximal tubules and high level, basolateral staining in distal tubules. Pkd2 expression is first detected in the medullary collecting ducts at postnatal day 14. Outside of the kidney, Pkd2 expression is widely distributed in utero and more restricted postnatally. The greatest intensity of staining is seen in the fetal but not adult adrenal cortex and in red blood cell precursors. Expression also is seen in multiple endocrine organs, in cardiac, skeletal, and smooth muscle, and in multiple mesenchymal tissues. The diffuse distribution and early expression of Pkd2 suggest a fundamental developmental role. The persistent strong expression in adult kidney is consistent with a more organ-specific function in the maintenance of the mature metanephric tubule.

Animals↗

PubMed1999

The rat pkd2 protein assumes distinct subcellular distributions in different organs.

Mutations in the PKD2 gene account for approximately 15% of all cases of autosomal-dominant polycystic kidney disease. In the present study the cellular distribution of the Pkd2 protein was investigated by immunohistochemistry in different rat organs. Although the Pkd2 protein showed a widespread expression, a strikingly different distribution of the protein was observed between individual organs. Whereas in renal distal tubules and in striated ducts of salivary glands a basal-to-basolateral distribution of Pkd2 was found, a punctate cytoplasmic location was detected in the adrenal gland, ovary, cornea, and smooth muscle cells of blood vessels. Interestingly, in the adrenal gland and ovary, the rat Pkd2 protein was more heavily N-glycosylated than in the kidney and salivary gland. These results suggest that Pkd2 accomplishes its functions by interacting with proteins located in different cellular compartments. The extrarenal expression pattern of the Pkd2 protein hints at other candidate sites of disease manifestations in patients carrying PKD2 mutations.

Adrenal Glands↗

PubMed1999

Aberrant splicing in the PKD2 gene as a cause of polycystic kidney disease.

It is estimated that approximately 15% of families with autosomal dominant polycystic kidney disease (ADPKD) have mutations in PKD2. Identification of these mutations is central to identifying functionally important regions of gene and to understanding the mechanisms underlying the pathogenesis of the disorder. The current study describes mutations in six type 2 ADPKD families. Two single base substitution mutations discovered in the ORF in exon 14 constitute the most COOH-terminal pathogenic variants described to date. One of these mutations is a nonsense change and the other encodes an apparent missense variant. Reverse transcription-PCR from patient lymphoblast RNA showed that, in addition, both mutations resulted in out-of-frame splice variants by activating cryptic splice sites via different mechanisms. The apparent missense variant produced such a strong splicing signal that the processed transcript from the mutant chromosome did not contain any of the normally spliced, missense product. A third mutation, a nonconservative missense change effecting a negatively charged residue in the third transmembrane span, is likely pathogenic and defines a highly conserved residue consistent with a potential channel subunit function for polycystin-2. The remaining three mutations included two frame shifts resulting from deletion of one or two bases in exons 6 and 10, respectively, and a nonsense mutation due to a single base substitution in exon 4. The study also defined a novel intragenic polymorphism in exon 1 that will be useful in analyzing "second hits" in PKD2. Finally, the study demonstrates that there are reduced levels of normal polycystin-2 protein in lymphoblast lines from PKD2-affected individuals and that truncated mutant polycystin-2 cannot be detected in patient lymphoblasts, suggesting that the latter may be unstable in at least some tissues. The mutations described will serve as critical reagents for future functional studies in PKD2.

Humans↗

PubMed1999

Effect of applying lactic acid bacteria isolated from forage crops on fermentation characteristics and aerobic deterioration of silage.

Two selected strains, Lactobacillus casei FG 1 and Lactobacillus plantarum FG 10 that were isolated from forage crops were used as additives at 1.0 x 10(5) cfu/g of fresh matter to alfalfa, Italian ryegrass, and sorghum, and their effect on fermentation characteristics and aerobic deterioration of silage was studied. The three silages treated with strains FG 1 or FG 10 were well preserved; had significantly lower pH values, butyric acid, propionic acid, and ammonia N concentrations, gas production, and dry matter losses; and had significantly higher contents of residual water-soluble carbohydrates and lactic acid than did the respective control silages. Yeast counts were high in all treated silages and increased rapidly during aerobic exposure. As a result, treated silages spoiled faster upon aerobic exposure than did the respective control silages. Most yeasts isolated from deteriorated silages showed high tolerance to lactic acid but low tolerance to butyric acid, and they were able to grow at low pH conditions and assimilate lactic acid. The results confirmed that L. casei and L. plantarum improved fermentation quality but did not inhibit the growth of silage yeast or aerobic deterioration of the silage.

Aerobiosis↗

PubMed1999

Identification and characterization of Enterococcus species isolated from forage crops and their influence on silage fermentation.

Forty-eight strains of lactic acid bacteria were isolated from forage crops, and their identification, characterization and influence on silage fermentation were studied. All isolates were Gram-positive, short-chain-forming, catalase-negative, and facultatively anaerobic cocci that did not produce gas from glucose, only formed L-lactic acid, and were able to grow at pH 9.6%, in 6.5% NaCl, or with 40% bile, but not below pH 4.5. These isolates were commonly isolated from forage crops, and they were divided into four groups (A, B, C, and D) according to sugar fermentation characteristics. Selected strains of FA 5, FA 27, FA 45, and FA 57 were identified as Enterococcus hirae, E. faecalis, E. casseliflavus, and E. mundtii, respectively, on the basis of DNA-DNA homology, Strains FA 5, FA 27, FA 45, and FA 57 and two strains from commercial inoculants, LC 10 (Lactobacillus casei) and LP 15 (L. plantarum), were used as additives to alfalfa and guinea grass silages. Alphalfa and guinea grass silages inoculated with LC 10, LP 15, FA 5 + LC 10, and FA 5 + LP 15-treatments in alfalfa and guinea grass silages had significantly lower pH values, contents of butyric acid and ammonia nitrogen, gas production, and dry matter losses compared with the control silage after 60 d of fermentation. However, the E. hirae FA 5, E. faecalis FA 27, E. casseliflavus FA 45, and E. mundtii FA 57-inoculated silages gave similar values to the control in both types of silage. The FA 27 + LC 10 and FA 27 + LP 15-inoculated silages did not differ in fermentation quality from LC 10 and LP 15-inoculated silages alone. The results confirmed that Enterococcus species were not able to improve silage quality.

Bacteria, Anaerobic↗

PubMed1999

Cloning of Schistosoma japonicum Chinese strain 22.6kD membrane-associated protein (Sj-22.6) gene and its overproduction on Escherichia coli.

A 567bp DNA fragment was amplified from Schistosoma japonicum adult worm mRNA by RT-PCR. Sequence analysis revealed that this fragment contained S. Japonicum Chinese strain membrane-associated protein (Sj-22.6) gene. Then this gene was cloned into the expression vector pGEX-4T, and subsequently expressed in Escherichia coli. The recombinant GST-fusion protein was purified by glutathione agarose affinity chromatography. Its molecular weight was about 48 kD. The yield of expression was around 40 mg/L E.coli culture. The immunological test suggested that the recombinant protein had good antigenity which could make a good basis for the research of its immunological function in Schistosomiasis.

Animals↗

PubMed1999

[The hemoprotective effect of platelet factor 4 (PF4) and tetrapeptide AcSDKP].

OBJECTIVE: To study the effects of platelet factor 4(PF4) and tetrapeptide N-acetyl-Ser-Asp-Lys-Pro(AcSDKP) on hemopoietic progenitors in mice treated with 5-Fluorouracil (5-FU). METHODS: Mice were injected with PF4 (40 micrograms/kg) or AcSDKP (4 micrograms/kg) twice at 6 h intervals, and 20 h after the second injection they were given one injection of 5-FU (150 mg/kg), and the high proliferative potential-colony forming cell (HPP-CFC), burst-forming unit erythroid (BFU-E), colony forming unit megakaryocyte (CFU-MK), and megakaryocyte (MK) were examined 6, 8 and 13 days later. RESULTS: The administration of PF4 or AcSDKP resulted in a significant increase of the number of HPP-CFC on days 6-8 and BFU-E and CFU-GM on day 8 when compared to 5-FU alone. Furthermore, PF4 was found to increase significantly the number of CFU-MK and MK on day 8, which was not observed with AcSDKP. CONCLUSION: PF4 or AcSDKP accelerate the recovery in vivo of HPP-CFC, CFU-GM and BFU-E after 5-FU treatment but their effect may be different on megakaryocytic progenitors. Both molecules may have a hemoprotective effect against chemotherapeutic agents.

Animals↗

PubMed1999

Effect of benzene, toluene, xylene on the semen quality of exposed workers.

OBJECTIVE: To examine the effects on semen and sperm quality of workers after a short and long term exposure to benzene, toluene, and xylene. METHODS: The semen and blood of 24 married workers exposed to benzene, toluene, and xylene from shoemaking, spray painting, or paint manufacturing factories were collected. The concentration of benzene, toluene, and xylene in the blood and semen was determined by using headspace chromatographic method. Routine sperm test was carried out and acrosin activity detected. RESULTS: The results showed that benzene, toluene, and xylene were found in the blood and semen of some ex-workers in a working environment where the air concentration of benzene, toluene, and xylene exceeded the maximum allowable concentration (MAC). This result was not found in workers of the control group. There were also some effects on the quality of semen in the exposed workers. For example, the percentage of semen with liquefaction time exceeding 30 minutes increased. The sperm vitality, motility and acrosin activity decreased. At the same time, there were a positive correlation between liquefaction time and the level of toluene in semen, and a negative correlation between sperm vitality, sperm activity or acrosin activity and working history. CONCLUSIONS: The results suggested that the mixture could affect the quality of semen and sperm, which might be the main reason of the abnormal pregnancy outcome among the wives of workers exposed to benzene, toluene, and xylene. Further studies are, however, required to confirm these findings.

Acrosin↗

PubMed1999

[Localization of a FLT3 ligand isoform in human tissues].

OBJECTIVE: To explore the localization of a human FLT3 ligand isoform deleted 139 bp of extracellular region. METHODS: Localization of the FLT3 ligand isoform in human tissues was studied by using PCR and RT-PCR. The PCR products were identified by DNA sequencing. RESULTS: FLT3 ligand was expressed in liver, fetal liver, bone marrow, muscle, kidney and peripheral blood cells and in four leukemia cell lines, but not in brain, while the FLT3 ligand isoform only in fetal liver and bone marrow. CONCLUSION: The FLT3 ligand isoform was expressed in hematopoietic cells and might be involved in hematopoiesis regulation.

Humans↗

PubMed1999

[MAL gene is down-regulated substantially in human esophageal cancer].

OBJECTIVE: To investigate the status of expression of MAL gene in human esophageal cancer. METHODS: Expression of MAL gene was analyzed by Northern blot and/or RT-PCR in 41 pairs of human esophageal cancer tissues and matched adjacent normal mucosa, and three human esophageal cancer cell lines EC109, EC8712 and EC9706. MAL gene was analyzed by PCR in the three esophageal cancer cell lines. RESULTS: MAL gene expression was down-regulated substantially or barely detectable in 93% (38/41) of human esophageal cancer tissues while expressed at high level in all matched adjacent normal esophageal mucosa. In all 3 human esophageal cancer cell lines, expression of MAL gene was not detectable. PCR analysis showed that the MAL gene fragment analyzed was intact in the three esophageal cancer cell lines. CONCLUSION: Down-regulation of MAL gene expression is of frequent occurrence in human esophageal cancer.

Down-Regulation↗

PubMed1999

[Clinical study on effect of Chinese herbal medicine on liver damage caused by hepatic artery chemoembolization].

OBJECTIVE: To observe the effect of Chinese herbal medicine on hepatic artery chemoembolization caused liver damage. METHODS: One hundred and ten patients, who received hepatic artery chemoembolization, were divided into two groups, 60 patients in the treated group were treated with Qinggan Jiedu Sanjie Decoction and the other 50 Patients in the control group treated with routine western medicine. The changes of liver function, cirrhosis incidence and exacerbation rate of both groups were observed. RESULTS: The total liver function deterioration rate of the treated group, according to Child's grading standard, was 46.67%, while that of the control group was 68.00%, the former was much lower than the latter (P < 0.05). The cirrhosis incidence and exacerbation rate in the treated group were 35.00% (7/20) and 50.00% (20/40) respectively, while in the control group, they were 65.00% (13/20) and 76.67% (23/30) respectively. The difference between the two groups was also significant (P < 0.05). CONCLUSION: Qinggan Jiedu Sanjie Decoction has some effect on alleviating and preventing hepatic damage caused by hepatic artery chemoembolization.

Adult↗

PubMed1999

[Curettage plus cement reconstruction for treating giant cell tumor of limbs].

OBJECTIVE: To evaluate curettage plus cement reconstruction in the treatment of giant cell tumor (GCT) of limbs. METHODS: 125 patients with GCT of limbs were treated with curettage plus cement reconstruction. They were 62 men and 63 women aged from 12 to 71 years, 101 patients had primary GCT and 24 had recurrence of GCT. The recurrence at the knee was noted in 100 patients (80%). RESULTS: 125 patients were followed-up for 96 months (range 13 - 194 months). The recurrence rate was 12.7% in the primary group and 10.3% in the recurrent group. Two patients were infected. Joint functions were excellent. CONCLUSIONS: Curettage plus cement reconstruction is safe and effective in treating local GCT of limbs. The key the method is aggressive curettage of the lesion via a bone window. Cement is adjuvant therapy only.

Adolescent↗