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Biomedical subjects

L Lin

Publications and source records attributed to L Lin.

At least 361 records · Page 20Linked to original sources
PubMed1990

Reciprocal effects of dexamethasone on vasodilatory responses to arachidonic acid and prostanoids in the isolated perfused rabbit kidney.

We reported that dexamethasone treatment of rabbits causes a reduction in renal vasoconstrictor responses to prostaglandin F2 alpha and U46619, an agonist at the thromboxane-endoperoxide receptor, but not to phenylephrine. The purpose of this study was to examine if dexamethasone treatment can affect the renal vasodilatory responses to prostacyclin (PGI2) and prostaglandin E2 (PGE2) in isolated Krebs-perfused kidneys constricted with phenylephrine. In kidneys from dexamethasone-treated rabbits, the vasodilatory response to PGI2 was reduced by 57%, whereas that to PGE2 was converted to a vasoconstrictor response. This effect of dexamethasone appears to be specific in that the renal vasodilatory responses to forskolin and to sodium nitroprusside were not affected by the steroid. Contrasting with the inhibitory effect of dexamethasone on prostanoid-induced renal vasodilation, treatment with dexamethasone augmented the renal vasodilatory response to arachidonic acid; for example, arachidonic acid, at 10 micrograms decreased perfusion pressure by 24.8 +/- 5.4 and 49.0 +/- 5.6 mm Hg in kidneys from vehicle- and dexamethasone-treated rabbits, respectively. The enhanced vasodilatory effect of arachidonic acid could not be attributed to increased renal formation of PGE2 and PGI2. In conclusion, dexamethasone interferes with prostanoid-mediated renal vasodilation, which is not associated with an impairment in renal responsiveness to direct activators of adenylate cyclase and guanylate cyclase. The reciprocal effect of dexamethasone on the renal vascular responses to arachidonic acid and vasodilatory prostanoids are indicative of a previously unrecognized influence of glucocorticoids on the renal arachidonate-prostaglandin system.

6-Ketoprostaglandin F1 alpha↗
PubMed1990

[Purge of malignant cells from bone marrow by hematoporphyrin derivatives and light exposure in vitro].

During autologous bone marrow graft in treatment of malignant diseases, it is critical to purge malignant cells from the marrow. In the present study, the sensitivity to photodynamic inactivation of 3 leukemic cell lines was compared with their counterpart normal hematopoietic cells. After mouse leukemic L1210 cells were treated with a preparation of hematoporphyrin derivatives, YHpD, 10 micrograms/ml for 1 h and irradiated with black light (peak wavelength 395 nm, light intensity 0.6 mW/cm2) for 5 min, the survival rate of clonogenic cells decreased to less than 10%, while that of bone marrow granulocyte-macrophage progenitor cells (CFU-GM) in DBA/2 mice remained at nearly normal level (greater than 80%). Similar results were obtained when human leukemic HL-60 cells were compared to human CFU-GM and mouse leukemic L615 cells to CFU-GM in 615 strain mice. It is suggested that hematoporphyrin photoradiation may be useful for selectivity killing leukemic cells in bone marrow.

Animals↗
PubMed1990

The variability of 24-hour, overnight 12-hour, and morning one-hour, urinary albumin excretion in normoalbuminuric and microalbuminuric hospitalized diabetics.

Albumin excretion rates (AER) of three consecutive days in different urine collection periods were measured in 7 hospitalized microalbuminuric diabetics (Ma DM) and 7 normoalbuminuric diabetics (Na DM). They were divided on the basis of an initial overnight urinary AER below or above 10 micrograms/min. The percentage of variation coefficients (% CV) of 24-hour, overnight 12-hour, and morning one-hour urine collections in Ma DM were 29.9%, 31.8% and 50.9%, respectively; while in Na DM group were 60.0%, 60.3% and 74.5%, respectively. There was no significant difference in the variation of AER among the three different urine collection procedures in both Ma DM and Na DM groups, or for similar urine collection between the two groups. The initial AER was compared to the subsequent two AERs in overnight 12-hour collection. The results were that three Ma DM patients had a subsequent AER below 10 micrograms/min and two Na DM patients had a subsequent AER above 10 micrograms/min on a single occasion. Therefore, the high variability of both groups would be expected to result in category changes. Multiple urine collections are needed to detect the early diabetic nephropathy for the hospitalized diabetics.

Aged↗
PubMed1990

[Anti-tumor effect of hernandezine and other components extracted from Thalictrum glandulosissimum].

The total alkaloids of T. glandulosissimum and its main component hernandezine were found to be effective for treatment of mice bearing P388 leukemia, S180 ascites and C26 colon cancer. Although hernandezine inhibited the growth of mouse L1210 cells and human oral cancer KB cells in vitro markedly, its inhibitory effect on normal hemopoietic progenitor cells (CFU-GM) in mice was relatively low. Preliminary results showed that hernandezine blocked cell-cycle transfer from G1 to S phase, and its cytocidal action might be cell cycle specific. In addition, two other components, thalidezine and isothalidezine, isolated from the same plant exerted similar inhibitory effect on L1210 cells.

Alkaloids↗
PubMed1990

[Application of equal value derivative spectrophotometry to the determination of coptis alkali in wanshi niuhuang qingxin pills].

The total coptis alkaloids Wanshi Niuhang Qingxin Pills were determined by equal value derivative spectrophotometry in this paper. Quantitative analysis of six mixtures of medicinal herbs can be done easily on the extract. The average recovery of berberine.HCl is 98.55 +/- 1.90% (CV). The method features good reproducibility, favorable stability and high sensitivity.

Alkaloids↗
PubMed1990

[Clinical observation and experimental study of the treatment of aplastic anemia by warming and tonifying the spleen and kidney].

84 cases observed were divided into 4 types according to principles of diagnosis and treatment based on an overall analysis of symptoms and signs, namely: Yang-deficiency of the Spleen and Kidney (62 cases, 73.8%), Yin-deficiency leads to internal heat (6 cases), deficiency of both the Heart and the Spleen (7 cases), and prostration of Qi after loss of blood (9 cases). The patients were treated with the method of warming and tonifying the Spleen and Kidney by using Er-Xian decoction of warming the Kidney. The three other types were also treated with the method after being relieved with the methods of tonifying the Heart and the Spleen, of nourishing Yin to relieve internal heat and cooling blood, and of strengthening Yang to stop chronic hemorrhage respectively so that function of the blood and Qi would promote each other and be improved. The total effective rate was 84.5%, and remission rate was 47.6% among 84 cases, but 91.9% and 50.0% in the type of Yang-deficiency of the Spleen and Kidney alone. Among the effective cases there was a remarkable improvement in the hemogram after treatment (P less than 0.001, less than 0.01), and the long-termed curative effect was also exciting. The mechanism of Er-Xian decoction of warming the Kidney was investigated through the nourishment of the hemopoiesis stem cell. The experiment showed that the decoction could increase CFU-S and GM-CFU in the bone marrow under the lower hemopoietic function of the bone marrow, and increase GM-CFU and CFU-E in the bone marrow of normal rats (P less than 0.001, less than 0.01, less than 0.05). The histological findings showed that there was a reduction in hemorrhage and hyperemia in the bone marrow between the decoction group and the control group, and the recovery of hemopoietic function was better than the latter.

Adolescent↗
PubMed1989

Heat shock-induced appearance of RNA polymerase II in karyoskeletal protein-enriched (nuclear "matrix") fractions correlates with transcriptional shutdown in Drosophila melanogaster.

Heat shock in vivo or brief incubation at moderately elevated temperatures (15 min at 37 degrees C) in vitro is required for the structural stability of proteinaceous karyoskeletal elements purified from Drosophila melanogaster (McConnell, M., Whalen, A. M., Smith, D. E., and Fisher, P. A. (1987) J. Cell Biol. 105, 1087-1098). We have found that the appearance of the two largest subunits of RNA polymerase II in karyoskeletal preparations is promoted by conditions identical to those which promote in vitro stability of karyoskeletal elements overall. Increased levels of polymerase II in karyoskeletal protein-enriched fractions correlate with decreased levels of nucleotide incorporation in nuclear transcription run-on assays. These results are not easily reconciled with the proposal that putative karyoskeletal elements such as the internal nuclear "matrix" are sites of active transcription in vivo.

Animals↗
PubMed1989

Lactate dehydrogenase and its isoenzyme activities in different parts of the normal human heart.

Activity and distribution of lactate dehydrogenase (LD) and its isoenzymes (LD1-5) were determined and both the heart (H) and muscle (M) subunit activities were calculated in myocardial samples from six brain dead human organ donors with normal hearts. Ten parts of each heart were analysed. LD1-3 were found to be the main LD isoenzymes. The LD1 activity predominated in all parts analysed. The activities of total LD, H subunit and LD1 increased from atria and auricular appendages via the right ventricle to the left ventricle. The H subunit activity varied more than twofold and the M subunit activity by only 20% between different locations of the heart. The left ventricular papillary muscle was found to have higher activities than other locations of both H and M subunits. It is concluded that the isoenzyme profile could be a metabolic adaptation to divergent work demand on the different heart chambers.

Adaptation, Physiological↗
PubMed1989

Regional distribution of citrate synthase and lactate dehydrogenase isoenzymes in the bovine heart.

Gradients of oxidative and glycolytic enzyme activities in the heart were studied by comparing samples taken from 10 locations from each of six bull hearts, within 30 min after slaughter. Citrate synthase (CS) was used as a marker of the oxidative potential and the lactate dehydrogenase (LD) subunits II and M as markers of aerobic glycolytic and anaerobic glycolytic potential respectively. CS activity in the ventricular tissue was greater than that of the right atrium, and no difference was found between the right and left ventricles. The left ventricular free wall had higher CS activity at the base than at the apex of the heart. Both the H and M subunit activities of LD increased in the following order: right atrium, right ventricle, ventricular septum, left ventricle. The left ventricular free wall showed higher H and M subunit activities at the base than at the apex. Within the left ventricular wall at the base, subendocardium had higher H and M subunit activities than subepicardium. The M subunit constituted the highest fraction of LD in the subendocardium and in the papillary muscle of the left ventricle. In conclusion, this study suggests that there are metabolic differences along both the radial and the longitudinal axes of the left ventricle and across the ventricular septum. These differences indicate that the greatest cellular stress, both aerobic glycolytic and anaerobic glycolytic in nature, occurs within the subendocardium at the base of the left ventricle and in the left ventricular papillary muscle.

Adenosine Triphosphate↗
PubMed1989

Use of 8-methoxypsoralen and long-wavelength ultraviolet radiation for decontamination of platelet concentrates.

Transmission of viral diseases through blood products remains an unsolved problem in transfusion medicine. We have developed a psoralen photochemical system for decontamination of platelet concentrates in which platelets are treated with long wavelength ultraviolet radiation (UVA, 320-400 nm) in the presence of 8-methoxypsoralen (8-MOP). Bacteria, RNA viruses, and DNA viruses ranging in genome size from 1.2 x 10(6) daltons, encompassing the size range of human pathogens, were inoculated into platelet concentrates and subjected to treatment. This system inactivated 25 to 30 logs/h of bacteria Escherichia coli or Staphylococcus aureus, 6 logs/h of bacteriophage fd, 0.9 log/h of bacteriophage R17 and 1.1 logs/h of feline leukemia virus (FeLV) in platelet concentrates maintained in standard storage bags. Platelet integrity and in vitro function before, immediately following photochemical treatment, and during prolonged storage after treatment, were evaluated by measuring: (1) extracellular pH; (2) platelet yields; (3) extracellular lactate dehydrogenase (LDH) levels; (4) platelet morphology; (5) platelet aggregation responsiveness; (6) thromboxane beta-2 (TXB-2) production; (7) dense body secretion; and (8) alpha granule secretion. These assays demonstrated that this photochemical inactivation system inactivated bacteria and viruses in platelet concentrates with minimal adverse effects on the in vitro function of platelets in comparison to untreated control concentrates maintained under current, standard blood bank conditions.

Blood Platelets↗
PubMed1988

Specificity of tumor necrosis factor toxicity for human mammary carcinomas relative to normal mammary epithelium and correlation with response to doxorubicin.

By using a unique short-term culture system capable of growing both normal and malignant breast epithelial tissue, human recombinant tumor necrosis factor (TNF) showed preferential cytotoxicity to malignant cells as compared to the corresponding nonmalignant cells. Most of the malignant specimens were sensitive to TNF with 13 of 18 specimens showing 90% inhibition of clonal growth (ID90) by less than 500 units of TNF per ml of culture fluid. In contrast, all 13 nonmalignant specimens tested clustered at the resistant end of the TNF response spectrum, with ID90 values being greater than 5000 units of TNF per ml of culture fluid. This differential sensitivity to TNF was seen in three cases in which malignant and nonmalignant breast epithelial tissues from the same patient were studied. To investigate the mechanism of resistance to TNF by normal cells, the presence of receptors for TNF was determined. Five of six cultures showed specific binding of 125I-labeled TNF and there was no relationship between the degree of resistance and the degree of specific binding. Simultaneous comparison of tumor responsiveness to doxorubicin and TNF revealed a positive correlation in ID90 values; these results may have important implications for the clinical use of TNF in cancer patients heavily pretreated with doxorubicin.

Breast↗
PubMed1988

Coenzyme Q10 content in different parts of the normal human heart.

Coenzyme Q10 (CoQ10) and citrate synthase (CS) activities were analysed in the myocardium of brain-dead organ donors (14-40 years). Different parts of the heart were studied: right and left auricular appendage, right and left atrium, right ventricle (septum and free wall) and left ventricle (septum, free wall, and papillary muscle). Freeze-dried, dissected myocardial samples were analysed for CoQ10 content by HPLC and CS activity by fluorometric technique. CoQ10 content in the normal human myocardium was lowest in auricular appendages and atria (0.25 +/- 0.06 mg X g-1 dry muscle), intermediate in right ventricle (0.37 +/- 0.05 mg X g-1 dm) and highest in left ventricle (0.42 +/- 0.07 mg X g-1 dm). CS activity showed the same relationship between these locations as CoQ10. The results suggest that there exist differences in CoQ10 content between different parts of the normal human myocardium. These differences were closely related to the differences in CS activity between corresponding parts. The differences between different parts of the heart may be related to divergent work demand, and the constant relationship between CS and CoQ10 may be related to their coupling to the mitochondrial oxidative metabolism.

Adult↗
PubMed1988

A micromethod for measuring carbonic anhydrase activity using 18O exchange between CO2 and H2O.

We have developed a method of measuring the activity and characteristics of carbonic anhydrase (CA) using the disappearance of 18O from CO2 in 1 ml of gas contained in a glass chamber as it exchanges with H2O in 0.01 ml 0.25 M NaHCO3 solution in a thin (25 micron) porous membrane. Serial gas samples (approximately 0.02 ml) are analyzed in a mass spectrometer to obtain the rate of disappearance of the label. The enzyme activity can be measured inside intact cell or particle membranes. As little as 10(-15) mol of high-activity type CA can be detected at 25 degrees C, and the activity of 200 times this amount can be measured. The uncatalyzed hydration reaction velocity constant was 0.056 +/- 0.004 s-1, in agreement with published data.

Bicarbonates↗
PubMed1987

Significance of elevated MB isoenzyme with normal creatine kinase in acute myocardial infarction.

The significance of elevated levels of the MB isomer of creatine kinase (CK-MB) when creatine kinase (CK) level is normal was studied in 400 patients with suspected acute myocardial infarction (AMI). In 350 patients both CK and CK-MB were elevated (group 1), in 21 only CK-MB was elevated (group 2), in 24 neither enzyme was elevated (group 3) and in 5 only CK was elevated (group 4). In 57% of patients in group 2 the CK level was doubled, with a characteristic enzyme curve, within the normal range, suggesting that an increase in CK had been missed because arbitrary definitions of "normal" were used. The median CK increase (60 IU/liter) in group 2 was greater than that in group 3 (23 IU/liter) (p less than 0.001). Patients in group 1 with small AMIs had a relative increase in CK similar to that in group 2. However, patients in group 2 had a lower baseline CK level so that peak CK did not become abnormally high despite a 5-fold increase in some patients. In patients in group 1 with small AMIs, CK was elevated in fewer samples than CK-MB. If only 2 samples were obtained in all patients, elevation of CK levels would have been missed in 63 group 1 patients, erroneously increasing the number of patients in group 2 fourfold (to 84 of 400, or 21%, instead of 21 of 400, or only 5%). Conversely, if patients in group 2 with a doubling of CK are excluded, the prevalence of elevated CK-MB with normal CK would be only 9 of 400 (2%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗