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Biomedical subjects

Y Cai

Publications and source records attributed to Y Cai.

At least 307 records · Page 17Linked to original sources
PubMed1992

The relationship between the changes in plasma atrial natriuretic peptide and renin angiotensin contents and hemodynamics in pulmonary hypertensive rats.

Pulmonary artery pressure (PAP) increased significantly in rats after hypobaric hypoxic exposure for 15 days (CH15) (P less than 0.001) and was maintained at the same level after prolonged hypoxic exposure for 40 days (CH40). There were no significant changes in carotid systolic and diastolic blood pressure in CH15 and CH40 rats. The contractility of the right and left ventricles of CH15 and CH40 rats showed no difference as compared with the control group. Plasma atrial natriuretic peptide (ANP) content in CH40 rats was obviously increased (P less than 0.001), while angiotensin II (AII) dropped markedly (P less than 0.05). Plasma renin activity was increased in both hypoxic groups (P less than 0.05 respectively). These results indicate that during chronic hypoxia, plasma ANP and the renin-angiotensin system (RAS) play an important role in the modulation of pulmonary as well as systemic hemodynamics. They may work cooperatively to limit the development of pulmonary hypertension and to maintain systemic blood pressure within the normal range.

Angiotensin II↗
PubMed1992

[Use of Cox's model in long-term survival analysis of cerebrovascular disease].

A long-term survival study on 885 cases of cerebrovascular disease was carried out. The results showed that after follow-up for 3, 5, and 8 years, the survival rates were 86.98%, 75.70% and 64.26% respectively, and all were lower obviously than that of the general population in the same district. The results of Cox's model analysis showed that recurrence, hypertension and age were the risk factors influencing the long-term survival of cerebrovascular disease, and the relative risks were 3.29, 2.17 and 1.65 respectively.

Adult↗
PubMed1992

A strategy for isolating differentiation-inducing complementary DNAs from human esophageal cancer cell line treated with retinoic acid.

Treatment of the human esophageal cancer cell line EC8712 with retinoic acid (RA) stopped the cell growth significantly and gave rise to terminal differentiation of the cells characterized by increased expression of involucrin gene. Two cDNA libraries were constructed from the parental and RA-treated cells respectively. Repeated subtractive hybridization of single-stranded plasmid DNA prepared from pooled colonies of cDNA library of the parental cells with cDNA probe generated from the RA-treated cells exhausted sequences common to both libraries of the cell. The unhybridized cDNA probe represented, therefore, the genes activated after RA-treatment. By using these enriched cDNAs as probe to screen the cDNA library constructed from the RA-treated cells thirty-nine positive colonies were obtained, of which two were specifically due to RA-induction. One of these two cDNA clones, designated as pRA538, has undergone further analysis and shown differentiation-inducing effect on parental cancer cells. A novel strategy for cloning genes involved in terminal differentiation of cancer cells is developed.

Carcinoma, Squamous Cell↗
PubMed1992

[Long-term prognosis following cerebrovascular disease].

A follow-up study on 885 cases of cerebrovascular disease who survived acute stage and were registered through prevalence survey in 1983, had been carried out for 5-8.5 years. The results shown that 34.58% died, 34.13% were independent and 31.29% needed help in various degrees. The older the age was, the worse the prognosis was. After 3, 5 and 8 years, the survival rates of the cases were 86.98%, 75.70% and 64.26% respectively, and all were lower than that in general population. The difference of survival rates between the ischemic cases and the hemorrhagic cases was not found.

Adult↗
PubMed1991

Use of a transposon with luciferase as a reporter to identify environmentally responsive genes in a cyanobacterium.

Anabaena, a filamentous cyanobacterium, is of developmental interest because, when deprived of fixed nitrogen, it shows patterned differentiation of N2-fixing cells called heterocysts. To help elucidate its early responses to a decrease in nitrogen, we used a derivative of transposon Tn5 to generate transcriptional fusions of promoterless bacterial luciferase genes, luxAB, to the Anabaena genome. Genes that responded to removal of fixed nitrogen or to other environmental shifts by increased or decreased transcription were identified by monitoring the luminescence of colonies from transposon-generated libraries. The Tn5 derivative transposed in Anabaena at ca. 1-4 x 10(-5) per cell and permitted high-resolution mapping of its position and orientation in the genome and facile cloning of contiguous genomic DNA.

Journal Article↗
PubMed1991

Chronic ethanol consumption depresses hypothalamic-pituitary-adrenal function in aged rats.

In separate experiments, nine (n = 20) and fifteen (n = 12) month old rats were treated with either 6% ethanol or 12% sucrose (to balance caloric intake) in the drinking water to examine the effect of chronic ethanol consumption on the hypothalamic-pituitary-adrenal axis of aged rats. Rats were maintained on these treatment regimens for thirty days and were killed by decapitation. Blood was collected and plasma concentrations of adrenocorticotropin (ACTH) and corticosterone were determined by radioimmunoassay. Adrenal glands were cleaned, quartered and used to test in vitro responsiveness to ACTH. Anterior pituitary glands from all 15 month old rats and one half of the nine month old rats were collected, frozen and extracted for measurement of tissue ACTH concentration. The remaining anterior pituitary glands from the nine month old rats were challenged with corticotropin releasing hormone (CRH) to test in vitro responsiveness. In nine month old rats, chronic ethanol consumption decreased plasma ACTH and corticosterone (P less than 0.05). Pituitary ACTH concentrations were unchanged in treated nine month old rats, but the amount of pituitary ACTH released in response to CRH was decreased (P less than 0.05) in rats consuming ethanol. In vitro responsiveness of the adrenal gland to ACTH in nine month old rats consuming ethanol was unchanged (P greater than 0.05). Plasma ACTH and corticosterone concentrations were also decreased in 15 month old rats chronically consuming ethanol (P less than 0.05). No differences were noted in responsiveness of the adrenal gland or in the amount of pituitary ACTH due to ethanol consumption in 15 month old rats (P greater than 0.05). The results of these experiments indicate that chronic ethanol consumption decreases hypothalamic-pituitary-adrenal function in aged rats.

Adrenocorticotropic Hormone↗
PubMed1991

Pathological changes of hyperphonated cat vocal folds.

To investigate the pathological changes of hyperphonated vocal folds 15 cats were used and over-cry was induced by mechanical stimuli. The longest experiment time was 15 weeks. All of the larynges were taken and the vocal folds were examined grossly and microscopically. The results were as follows: 1) liquid exudate accumulation beneath the epithelium developed in all of the experimental animals; 2) thickening of the epithelium was noticed in cats which had hyperphonated for more than 4 weeks; 3) acute laryngitis occurred in three cats.

Acute Disease↗
PubMed1991

Characterization of insertion sequence IS892 and related elements from the cyanobacterium Anabaena sp. strain PCC 7120.

IS892, one of the several insertion sequence (IS) elements discovered in Anabaena sp. strain PCC 7120 (Y. Cai and C. P. Wolk, J. Bacteriol. 172:3138-3145, 1990), is 1,675 bp with 24-bp near-perfect inverted terminal repeats and has two open reading frames (ORFs) that could code for proteins of 233 and 137 amino acids. Upon insertion into target sites, this IS generates an 8-bp directly repeated target duplication. A 32-bp sequence in the region between ORF1 and ORF2 is similar to the sequence of the inverted termini. Similar inverted repeats are found within each of those three segments, and the sequences of these repeats bear some similarity to the 11-bp direct repeats flanking the 11-kb insertion interrupting the nifD gene of this strain (J. W. Golden, S. J. Robinson, and R. Haselkorn, Nature [London] 314:419-423, 1985). A sequence similar to that of a binding site for the Escherichia coli integration host factor is found about 120 bp from the left end of IS892. Partial nucleotide sequences of active IS elements IS892N and IS892T, members of the IS892 family from the same Anabaena strain, were shown to be very similar to the sequence of IS892.

Amino Acid Sequence↗
PubMed1991

Characterization of the IS895 family of insertion sequences from the cyanobacterium Anabaena sp. strain PCC 7120.

A family of repetitive elements from the cyanobacterium Anabaena sp. strain PCC 7120 was identified through the proximity of one element to the psbAI gene. Four members of this seven-member family were isolated and shown to have structures characteristic of bacterial insertion sequences. Each element is approximately 1,200 bp in length, is delimited by a 30-bp inverted repeat, and contains two open reading frames in tandem on the same DNA strand. The four copies differ from each other by small insertions or deletions, some of which alter the open reading frames. By using a system designed to trap insertion elements, one of the elements, denoted IS895, was shown to be mobile. The target site was not duplicated upon insertion of the element. Two other filamentous cyanobacterial strains were also found to contain sequences homologous to IS895.

Amino Acid Sequence↗
PubMed1991

Effect of chronic hypoxia on endothelium-dependent relaxation and cGMP content in rat pulmonary artery.

This experiment was designed to determine whether chronic hypoxia affects endothelium-dependent relaxation and cGMP content of rat pulmonary artery (PA). Both Ach and ATP were found to induce endothelium-dependent relaxation of PA; and this relaxation was not prevented by indomethacin, but was completely abolished by methylene blue. Chronic hypoxia significantly depressed the endothelium-dependent relaxation: the relaxation responses of intra-PA (IPA) and extra-PA (EPA) to 10(-6) mol/L Ach in the hypoxic group were 61.3% and 59.2% of those in control, and the relaxation responses of IPA and EPA to 1.8 x 10(-5) mol/L ATP in the hypoxic group were 64.9% and 55.2% of those in the control, respectively. Chronic hypoxia significantly decreased the basic level and Ach-induced accumulation of cGMP in the PA. Our data suggest that chronic hypoxia might depress rat pulmonary artery endothelium-dependent relaxation through the inhibition of cytosolic soluble guanylate cyclase in vascular smooth muscle cells.

Acetylcholine↗
PubMed1991

[Experimental studies with Bergenia purpurascens, the frequency of micronucleus in NIH mice, the frequency of SCE, and chromosome aberration in human lymphocytes].

Bergenia purpurascens tablets were prepared according to the technological requirements of Chinese traditional medicine. Using these tablets to treat patients with esophageal epithelial cell proliferation and inflammation for five years in Lang Zhong and Yan Ting Counties, Sichuan Province, a cure rate of 88.7% was achieved, demonstrating that Bergenia purpurascens is a new and promising drug. However, in order to determine whether or not long period of administration will induce mutagenesis carcinogenesis, we carried out micronucleus, chromosomal aberration and sister chromatid exchange frequency tests. The results showed that the drug neither induces micronucleus formation nor chromosomal aberration and SCE. Therefore, we conclude that this drug is safe and without toxic side effects.

Animals↗
PubMed1991

[The inhibition of acetylcholine- and sodium nitroprusside-induced pulmonary artery relaxation by chronic hypoxia].

This experiment was designed to investigate whether chronic hypoxia could reduce pulmonary artery relaxation induced by acetylcholine and sodium nitroprusside (endothelium-dependent and endothelium-independent vasodilator, respectively). Male Wistar rats were divided into 3 groups: control, kept in air; CH4, in hypobaric chamber (8000 m above sea level) for 4 days; CH20, in hypobaric chamber (5000 m above sea level) for 20 days. All the hypoxic rats developed pulmonary hypertension. Rings of extra- (EPPA) or intra- (IPPA) pulmonary artery were suspended in an organ bath containing oxygenated Kreb's solution at 37 degrees C for relaxation/inhibition studies. The results showed that chronic hypoxia, CH4 and CH20, inhibited the relaxation response of both IPPA and EPPA to both acetylcholine and sodium nitroprusside. It is suggested that chronic hypoxia might attenuate the sensitivity and reactivity of the pulmonary artery to both acetylcholine and sodium nitroprusside through the inhibition of guanyl cyclase activity in smooth muscle.

Acetylcholine↗
PubMed1990

Antifungal activity in human cerebrospinal fluid and plasma after intravenous administration of Allium sativum.

Commercial Allium sativum (garlic) extract was given intravenously to two patients with cryptococcal meningitis and three patients with other types of meningitis. Plasma titers of anti-Cryptococcus neoformans activity rose twofold over preinfusion titers. Anti-C. neoformans activity was detected in four of five cerebrospinal fluid samples but not in pooled normal cerebrospinal fluid.

Antifungal Agents↗
PubMed1990

Deep cerebral infarcts in the People's Republic of China.

We reviewed computed tomograms and clinical characteristics for 1,124 consecutive stroke patients from Shanghai, People's Republic of China. While there were many similarities between lacunar syndromes in these patients and patients from Europe and the United States, several differences were noted. Deep cerebral infarcts identified by computed tomography were more common in patients from Shanghai and accounted for 27% of all ischemic infarcts. Small deep infarcts occurred more commonly in women from Shanghai (44%) than in women from the West. Deep cerebral infarcts in patients from Shanghai were larger than those usually seen in patients from the West. The mean infarct volume in patients from Shanghai was 2.4 ml, and 49% were giant lacunes (greater than 15 mm in maximal diameter).

Aged↗