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Biomedical subjects

Z Yang

Publications and source records attributed to Z Yang.

At least 883 records · Page 49Linked to original sources
PubMed1992

[Determination of serum creatinine kinase MM isoforms in assessing reperfusion after acute myocardial infarction].

Creatine kinase(CK), aspartate aminotransferase (AST), alpha-hydroxybutyrate dehydrogenase (HBDH), lactate dehydrogenase (LD) and LD isoenzymes, CK-MB isoenzymes and CK-MM isoforms were measured in 17 acute myocardial infarction (AMI) patients treated with thrombolysis resulting in reperfusion and 2 not resulting in reperfusion as well as 71 treated conventionally to assess reperfusion. The results showed that the peak of the ratio of MM3 to MM1 was attained significantly earlier in patients with reperfusion than in those conventionally treated and those without reperfusion, and this ratio is considered to be a good indicator to assess reperfusion. The results were similar to those of previous reports. The peak in all the 17 patients with confirmed reperfusion was attained within 9 hours after onset of AMI, while only 9 of the 73 patients in the group without reperfusion had their peaks within 9 hours. The diagnostic efficiency was 94%. The authors suggested a new indicator for assess reperfusion. An increase of CK-MM3 over 10% from the first to the second hour after treatment with urokinase was found in 15 of the 17 urokinase-treated patients with reperfusion. The diagnostic efficiency was also 94%. We consider that it is an indicator as good as the peak of ratio of MM3/MM1. Furthermore, with this indicator, it is possible to assess reperfusion in two hours after treatment with urokinase.

Adult↗
PubMed1992

[Study of the estrogen receptor and progesterone receptor in human cervical carcinoma].

Three hundred and twelve different cervical specimens have been tested for estrogen (ER) and progesterone receptor (PR) content with dextran-coated charcoal method (DCC). The results showed that the concentrations of ER and PR in normal cervical tissues were higher than those in malignant cervical tissues, and that the percentage of positive scores for ER and PR in cervical squamous epithelial tissues were higher than that in malignant cervical tissues. That the variances of ER and PR in cervical malignant tumors were not parallel suggested that the production or/and the mechanism of receptor action might be impaired. The percentage of positive scores for ER was not correlated with the clinical stages whereas that of PR was inversely proportional to clinical stages. That some patient with cervical cancer had high level of PR and had both ER and PR positive implied the possibility for endocrine therapy. The content and distribution of ER and PR in normal cervical tissues are consistent with the effects of sex hormone.

Carcinoma, Squamous Cell↗
PubMed1992

[The antigastroulcerative activity of beta-sitosterol-beta-D-glucoside and its aglycone in rats].

Beta-sitosterol-beta-D-glucoside and its aglycone (the major constituent of the seed oil of Hippophae rhamnoides L.) were investigated for their antigastroulcerative activity in rats. Two experimental gastric ulcer models were selected: chronic acetic acid-induced ulcers and cold stress-induced ulcers. Both the glucoside and its aglycone showed antiulcerative activity in chronic acetic acid-induced gastric ulcer models, and their effects were at least comparable to the effects of wishupin in combination with cimetidine. The effect of aglycone appears better than the glucoside's. Glucoside also showed visibly antiulcerative effects on cold stress-induced ulcers, but wishupin combined with cimetidine did not have such effects.

Acetates↗
PubMed1992

[Traumatic orbital wall fracture].

Thirteen patients with orbital wall fracture by trauma were reported. Among them, 6 cases were inferior-wall type, another 6 cases were interioinferior-wall type, and 1 case with interior-wall type. The clinical manifestation was mainly enophthalmos. All of patients were treated with plastic operation through nasal sinuses and fixed with national osseous cement. 11 cases were cured, 1 case was improved, 1 case had no change.

Adolescent↗
PubMed1992

Different effects of activated platelets in the right gastroepiploic and internal mammary arteries. Implications for coronary artery grafting.

The right gastroepiploic artery is increasingly utilized as an alternative coronary bypass conduit, although postoperative spasm can represent a problem. Platelet-vessel wall interactions are important determinants of graft function and patency. We studied the effects of activated platelets in porcine and human gastroepiploic and mammary arteries. Arterial rings were suspended in organ chambers for isometric tension recording. In the porcine and human gastroepiploic arteries with or without endothelium contracted with norepinephrine, activated platelets evoked only further and strong contraction. In contrast, in the porcine and human mammary arteries, endothelium-dependent relaxations to platelets mediated by nitric oxide were noted, particularly in rings preincubated with the thromboxane A2 receptor antagonist SQ-30741 and the 5-hydroxytryptamine (5HT2)-serotonergic receptor antagonist ketanserin. Although endothelium-dependent and endothelium-independent relaxation to bradykinin and the nitrovasodilator 3-morpholino sydnonimine were more pronounced in the gastroepiploic than in the mammary artery, norepinephrine, serotonin, and potassium chloride evoked much stronger contractions in the former than in the latter. Thus activated platelets induce pronounced contraction of the gastroepiploic artery that may contribute to postoperative spasm. The administration of antiplatelet drugs and vasodilators that prevent the effects of thromboxane A2 and serotonin may be beneficial for gastroepiploic graft function.

Adenosine Diphosphate↗
PubMed1992

[Effect of Chinese-made vesnarinone on experimental heart failure of dog].

Intravenous drip of sodium pentobarbital 6 mg/kg per min induced obvious heart failure of anesthetic dogs (n = 11) followed by an infusion of 0.25 mg/kg per min to maintain the heart failure state. The Chinese-made vesnarinone 3 mg/kg was injected, followed by an infusion of 0.1 mg/kg per min, or the solvent in the same volume, for 30 min. Vesnarinone increased significantly and instantly the cardiac output and left ventricular maximum + dp/dt, which almost recovered to normal at the end of the infusion and also significantly increased 30 min after administration. The positive inotropic effect of vesnarinone was not accompanied by an increase in the heart rate and the blood pressure. The results of our experiment reveal that the Chinese-made vesnarinone has a potent and relatively selective positive action on heart failure of dogs.

Animals↗
PubMed1992

Similar endothelium-dependent relaxation, but enhanced contractility, of the right gastroepiploic artery as compared with the internal mammary artery.

The right gastroepiploic artery is an alternative coronary bypass graft. The excellent graft function of the internal mammary artery has been related to its physiologic properties, particularly to endothelial function. Isolated artery rings were suspended in organ chambers for recording of isometric tension. Norepinephrine and potassium chloride evoked threefold greater contractions in the gastroepiploic artery than in the mammary artery (p less than 0.01 to 0.05), whereas the sensitivity to the catecholamine was comparable. Acetylcholine induced endothelium-dependent relaxations, but the sensitivity (pD2: 6.7 +/- 0.3) and maximal relaxation (81% +/- 9%) were slightly less in the gastroepiploic artery than in the mammary artery (pD2: 7.6 +/- 0.2; 100% +/- 0%; p less than 0.05). Histamine induced endothelium-dependent relaxations with a similar sensitivity (pD2: 7.5 +/- 0.3 and 7.2 +/- 0.1), whereas the maximal relaxation was slightly enhanced in the gastroepiploic artery. The relaxation to the nitric oxide donor SIN-1 was identical in the two arteries. Thus the right gastroepiploic artery exhibits better contractility than the internal mammary artery but comparable endothelium-dependent and endothelium-independent relaxations. The good endothelial function of the gastroepiploic artery might be important for graft function and patency, whereas the enhanced contractility may facilitate vasospasm, especially in the presence of high circulating levels of catecholamines.

Acetylcholine↗
PubMed1991

Delineation of a previously unrecognized cis-acting element required for HLA class II gene expression.

The cis-acting DNA sequences that control expression of the HLA-DPA and HLA-DQB promoters have been investigated in detail. A set of recombinant plasmids containing 5' promoter deletions as well as site-directed mutants of the DPA and DQB genes were fused to a reporter gene and transfected into human B and interferon gamma (IFN-gamma)-inducible cells. A previously unrecognized cis element, which is essential both for transcription induced by IFN-gamma in several cell types and for constitutive class II expression in B cells, in addition to the well known X and Y boxes, has been defined. This sequence, which spans nucleotides -107 to -98 and -146 to -137 of the DPA and DQB promoters, respectively, has been called the J element. Some evidence for function of a fourth element, the S element, is also presented.

Base Sequence↗
PubMed1991

Human and rat mesangial cell receptors for glucose-modified proteins: potential role in kidney tissue remodelling and diabetic nephropathy.

Advanced glycosylation endproducts (AGEs) are derived from the nonenzymatic addition of glucose to proteins. AGEs have been found to accumulate on tissue proteins in patients with diabetes, and their accumulation is thought to play a role in the development of diabetic complications. The finding that macrophages and endothelial cells contain AGE-specific receptors led us to examine whether mesangial cells (MCs) also possess a mechanism for recognizing and processing AGEs. Membrane extracts isolated from rat and human MCs were found to bind AGE-bovine serum albumin (BSA) in a saturable fashion, with a binding affinity of 2.0 +/- 0.4 x 10(6) M-1 (500 nM). The binding was specific for the AGE adduct, since AGE-modified collagen I and ribonuclease both competitively inhibited 125I-AGE-BSA binding to MC membranes, while the unmodified proteins did not compete. Binding of AGE proteins was followed by slow internalization and degradation of the ligand. Ligand blotting of MC membrane extracts demonstrated three distinct AGE-binding membrane proteins of 50, 40, and 30 kD. Growth of MCs on various AGE-modified matrix proteins resulted in alterations in MC function, as demonstrated by enhanced production of fibronectin and decreased proliferation. These results point to the potential role that the interaction of AGE-modified proteins with MCs may play in vivo in promoting diabetic kidney disease.

Adult↗
PubMed1991

Advanced glycosylation end products in patients with diabetic nephropathy.

BACKGROUND: Glucose reacts nonenzymatically with proteins in vivo, chemically forming covalently attached glucose-addition products and cross-links between proteins. The excessive accumulation of rearranged late-glucose-addition products, or advanced glycosylation end products (AGEs), is believed to contribute to the chronic complications of diabetes mellitus. METHODS: To elucidate the relation of AGEs to diabetic complications, we used a radioreceptor assay to measure serum and tissue AGEs in diabetic (Types I and Type II) and nondiabetic patients with different levels of renal function. Serum AGEs were measured as a low-molecular-weight (less than or equal to 10 kd) peptide fraction and a high-molecular-weight (greater than 10 kd) protein fraction. RESULTS: The mean (+/- SD) AGE content of samples of arterial-wall collagen from 9 diabetic patients was significantly higher than that of samples from 18 nondiabetic patients (14.5 +/- 5.2 vs. 3.6 +/- 1.5 AGE units per milligram, P less than 0.001). Moreover, diabetic patients with end-stage renal disease had almost twice as much AGE in tissue as diabetic patients without renal disease (21.3 +/- 2.8 vs. 11.5 +/- 1.9 AGE units per milligram, P less than 0.001). The AGE levels in both serum fractions were elevated in the patients with diabetes, and the levels of AGE peptides correlated directly with serum creatinine (P less than 0.001) and inversely with creatinine clearance (P less than 0.005), suggesting that levels of AGE peptides increased with the severity of diabetic nephropathy. In six patients with diabetes who required hemodialysis, the levels of AGE peptides were five times higher than in eight normal subjects (82.8 +/- 9.4 vs. 15.6 +/- 3.4 AGE units per milliliter, P less than 0.001). In another group of diabetic patients the mean serum creatinine level, which decreased by 75 percent during a session of hemodialysis, whereas the level of AGE peptides decreased by only 24 percent. Serum levels of AGE peptides were normal in two patients with normal serum creatinine levels after renal transplantation. CONCLUSIONS: AGEs accumulate at a faster-than-normal rate in arteries and the circulation of patients with diabetes; the increase in circulating AGE peptides parallels the severity of renal functional impairment in diabetic nephropathy.

Adult↗
PubMed1991

Two novel rat liver membrane proteins that bind advanced glycosylation endproducts: relationship to macrophage receptor for glucose-modified proteins.

Advanced glycosylation endproducts (AGEs), the glucose-derived adducts that form nonenzymatically and accumulate on tissue proteins, are implicated in many chronic complications associated with diabetes and aging. We have previously described a monocyte/macrophage surface receptor system thought to coordinate AGE protein removal and tissue remodeling, and purified a corresponding 90-kD AGE-binding protein from the murine RAW 264.7 cell line. To identify AGE-binding proteins in normal animals, the tissue distribution of 125I-AGE rat serum albumin taken up from the blood was determined in rats in vivo. These uptake studies demonstrated that the liver was a major site of AGE protein sequestration. Using a solid-phase assay system involving the immobilization of solubilized membrane proteins onto nitrocellulose to monitor binding activity, and several purification steps including affinity chromatography over an AGE bovine serum albumin matrix, two rat liver membrane proteins were isolated that specifically bound AGEs, one migrating at 60 kD (p60) and the other at 90 kD (p90) on SDS-PAGE. NH2-terminal sequence analysis revealed no significant homology between these two proteins nor to any molecules available in sequence databases. Flow cytometric analyses using avian antibodies to purified rat p60 and p90 demonstrated that both proteins are present on rat monocytes and macrophages. Competition studies revealed no crossreactivity between the two antisera; anti-p60 and anti-p90 antisera prevented AGE-protein binding to rat macrophages when added alone or in combination. These results indicate that rat liver contains at least two novel and distinct proteins that recognize AGE-modified macromolecules, although p90 may be related to the previously described 90-kD AGE receptor isolated from RAW 264.7 cells. The constitutive expression of AGE-binding proteins on rat monocytes and macrophages, and the sequestration of circulating AGE-modified proteins by the liver, provides further evidence in support of a role for these molecules in the normal removal of proteins marked as senescent by accumulated glucose-derived covalent addition products, or AGEs.

Aging↗
PubMed1991

Genomic structure of murine macrophage inflammatory protein-1 alpha and conservation of potential regulatory sequences with a human homolog, LD78.

The gene for a murine macrophage inflammatory cytokine, MIP-1 alpha, belongs to a newly recognized superfamily encoding small, inducible peptides shown to be up-regulated in association with cellular activation or transformation (tentatively designated the scy, or small cytokine, gene family). Secreted scy family peptides as a group, and MIP-1 alpha in particular, have inflammatory and mitogenic activities, and the family has been divided into CXC and CC subfamilies according to the spacing of conserved cysteine residues in the primary amino acid sequences. We have isolated and characterized a genomic clone encoding the CC subfamily member MIP-1 alpha. The organization of the murine MIP-1 alpha gene into three exons interrupted by two introns is identical to that found for other members of the CC subfamily (e.g., huLD78, muJE, huJE/MCP-1, muTCA3, and hul-309), which has been taken as evidence of evolution from a common ancestral gene. With the exception of the ratPF4 gene, which shares the two-intron/three-exon pattern typical of the CC subfamily, sequenced genes encoding CXC subfamily peptides (e.g., hulL-8 and hulP-10) include an additional intervening sequence that creates a fourth exon. Genomic nucleotide sequences 5' of the MIP-1 alpha cap site are highly homologous to corresponding regions of the human gene encoding a CC peptide variously designated as LD78/GOS19/pAT464, including consensus regulatory motifs in common, reinforcing the contention that MIP-1 alpha and LD78 may be interspecies homologs.

Amino Acid Sequence↗
PubMed1991

Different potency of endothelium-derived relaxing factors against thromboxane, endothelin, and potassium chloride in intramyocardial porcine coronary arteries.

Endothelium-derived relaxing factors (EDRFs) and prostacyclin (PGI2) released from endothelial cells are potent vasodilators; endothelin-1 and thromboxane A2 may be their physiological antagonists. Interactions between these vasodilators and vasoconstrictors were studied in isolated intramyocardial porcine coronary arteries suspended in myographs for isometric tension recording. Endothelium-dependent relaxations to bradykinin and serotonin were reduced to a similar extent in arteries contracted with endothelin-1 and KCl as compared to those contracted with the thromboxane analog U 46619 (p less than 0.05; n = 5-6). In contrast, relaxations to the nitric oxide donor SIN-1 were comparable. PGI2 was most potent in arteries exposed to U 46619, while its effects were inhibited in the presence of endothelin-1 or acetylcholine and prevented by KCl (p less than 0.05-0.0001; n = 5). At high concentrations PGI2 evoked contractions in arteries contracted with endothelin-1, acetylcholine, or KCl, but not in those with U 46619, which were prevented by the thromboxane receptor antagonist SQ 30741 (p less than 0.05; n = 5), indicating that PGI2 is a partial agonist for the thromboxane receptor. Thus, in intramyocardial porcine coronary arteries, contractile agonists differently interact with the release and action of EDRFs and PGI2. Both are most effective against contractions induced by thromboxane. In contrast, endothelin-1 and particularly KCl reduce the potency of these endogenous vasodilator systems.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1991

Differential activation of potato 3-hydroxy-3-methylglutaryl coenzyme A reductase genes by wounding and pathogen challenge.

Potato genes encoding 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) were expressed in response to pathogen, elicitor, and wounding. HMGR catalyzes the rate-limiting step in isoprenoid biosynthesis leading to accumulation of phytoalexins and steroid glycoalkaloids. Wounding caused increases in HMGR mRNA levels. A rapid and transient peak occurred 30 minutes after wounding, followed by a slower peak at 14 hours; both were correlated with increased enzyme activity. Induction of HMGR mRNA by the soft rot pathogen Erwinia carotovora subsp carotovora or arachidonic acid began 8 hours after challenge and continued through 22 hours. Potato HMGR is encoded by a gene family. An HMGR gene-specific probe was used to demonstrate that one isogene of the HMGR family is pathogen activated and is distinct from isogene(s) that are wound activated. This provides evidence that defense-related increases in HMGR activity are due to mRNA level increases and that HMGR isogenes are activated differentially by wounding or pathogen challenge.

Arachidonic Acids↗
PubMed1991

Redistribution of intraorgan blood flow in acute, hyperdynamic porcine endotoxemia.

In a standardized porcine model of acute, hyperdynamic endotoxemia the distribution of intraorgan blood flow within heart, kidney and brain was analyzed. Twelve pigs received either short-term (23 min) or long-term (205 min) continuous intravenous infusion of endotoxin (Salmonella abortus equi). A high cardiac output/low peripheral resistance state was maintained throughout the 3.5 h observation period. Total organ blood flow in heart, kidney and brain remained high; however, already small amounts of endotoxin provoked a significant redistribution of intraorgan blood flow within the left ventricle and the kidney. These characteristic alterations were absent in a control group of 5 animals subjected to the same protocol, but receiving 0.9% saline instead of endotoxin. Deterioration of respiratory function developed exclusively after continuous intravenous endotoxin infusion over 205 min, indicating incipient organ failure. Using electron microscopy, endothelial cells swelling and entrapment of blood cells in capillaries of the midmyocardium as well as severe ultrastructural damage in the kidney could be demonstrated already after 90 min of endotoxemia in two additional animals. It is concluded that already in the initial phase of acute endotoxemia, in the presence of high cardiac output and high global organ blood flow microcirculatory deterioration and organ failure develops. As small amounts of endotoxin are capable of inducing these alterations, earliest possible diagnosis of endotoxemia should be achieved in critically ill patients.

Acute Disease↗
PubMed1991

Forskolin-induced immunoreactive atrial natriuretic peptide (ANP) secretion and pro-ANP messenger ribonucleic acid expression of hypothalamic neurons in culture: modulation by glucocorticoids.

In the present studies the chronic effects of glucocorticoids and drugs activating cAMP-dependent pathways on the production and secretion of immunoreactive (ir) ANP from long term monolayer cultures of neonatal rat hypothalamic neurons were examined. Forskolin treatment increased ir-ANP release in a time-dependent and dose-related manner, with an EC50 of approximately 30 microM; at a lower dose of 10 microM, forskolin doubled ir-ANP release (P less than 0.01) compared to that in control cultures (mean +/- SEM, 9.6 +/- 0.3 pg/well; n = 4). While dexamethasone (DM) alone did not affect basal secretion of ir-ANP, 10 nM of the glucocorticoid significantly enhanced the effect of forskolin (10 microM) by raising ir-ANP release approximately 3 times that induced by forskolin alone (P less than 0.001). This potentiation of DM was both time dependent and dose responsive, with an EC50 of 1 nM; this effect was significantly suppressed by 100 nM RU38486, a glucocorticoid or type II receptor antagonist, but not by RU28318, a mineralocorticoid receptor antagonist. In addition, forskolin (10 microM) or DM (10 nM) alone significantly increased ir-ANP production approximately 1.4 times (P less than 0.05) and 1.3 times (P less than 0.05) over that of control cultures, respectively, whereas concurrent treatment with forskolin and DM increased ir-ANP production by approximately 1.8 times (P less than 0.01). These changes were reflected by a corresponding increment in the abundance of pro-ANP mRNA in the cultures, as demonstrated by Northern blot analysis. We conclude from the present findings that glucocorticoid- and cAMP-dependent pathways may modulate the function of ANP neurons in rat hypothalami by regulating the secretion and production of the neuropeptide at the genomic level.

Animals↗
PubMed1991

Three challenges of China's population in the 1990s.

China will encounter 3 challenges of its population problem in the 1990s. The 1st is the huge number of people born or population increase each year. The 3rd baby boom, which started at the mid-1980s, will last until abound 1997. The women entering into the age of peak childbearing (23 years old) exceed 11 million each year with an upper range of about 13 million. IN 1992, the number of women of fecund ages (22-29) in the whole country will reach 124 million, the largest number of fertile women in history. The net increase of population will be from 15.5 to 17.0 million for each hear. What is more serious is that the momentum of population increase will continue, instead of being checked by the year 2000. The next are the continuous increase of the aged population of 65 and over and the growing tendency of population aging ahead of economic development. China is a developing socialist country, huge in population, weak in economic development, with less-developed science, culture, and education. However, as a result of the decline in the proportion of children to the total population due to the decline in the birth rate in the 1970s, China's population has become an adult population from a young one in terms of the age structure, and will be an aged one very soon. China is facing the challenge of aging under economically less developed conditions. For developed countries, it took 80 years for the proportion of the aged population of 65 and over to increase from 7% to 17%; for China, it has taken only 40 years. It will certainly bring about a series of problems and difficulties upon the society to cope with such a huge number of elderly in an underdeveloped economy. The 3rd challenge is the increasing pressure on employment due to the continuous growth of working-age population (15-64). It is estimated that the working-age population will increase to 858 million by 2000, 20 million more than the sum of working-age population in all of the developed countries; and to 977 million by 2020. Since in a short period of time it is difficult to change the situation of labor supply greater than demand, the pressure on employment will continue to increase, with more than 15 million people entering the labor force or waiting for jobs each year. In particular, the rural surplus labor force will reach 233 million by 2000. This is signaled by the huge number of farmers who have rushed into big cities for work in recent years. It is far beyond the capability of the government to employ such a huge number of laborers because it would require an investment of at least 3600 billion yuan for fixed assets. It seems to me that the 3 population challenges stated above are not isolated but interact to restrict the process of China's economic and social development. The way out lies in developing production and doing a better job of economic construction, while also adopting comprehensive measures to make further efforts in practicing family planning to better control the overrapid growth of population and improve the quality of human resources.

Adult↗