Biomedical subjects

L Lin

Publications and source records attributed to L Lin.

At least 397 records · Page 22Linked to original sources

PubMed1991

Myocardial lactate dehydrogenase and its isoenzyme activities in transplanted human hearts.

Lactate dehydrogenase and its heart (H) and muscle (M) subunit activities were studied in right ventricular endomyocardial biopsies from eight transplanted human hearts and compared with five chronically failing hearts and six normal human hearts from brain-dead liver/kidney donors. Of the 17 transplant biopsies (taken 5-95 weeks postoperatively), only two showed histologic signs of chronic rejection: They were excluded from the group analysis. A higher proportion of the M subunit of lactate dehydrogenase (M%) was found in the transplanted and the chronically failing hearts than in the normal hearts, presumably reflecting increased myocardial anaerobic glycolytic stress. In the early post-transplantation period, M% was higher in the transplanted than in the chronically failing hearts. Thereafter M% gradually fell, but had not reached normal levels 1-2 years after transplantation. During that time it was similar to the values in the chronic-failure hearts. In the two biopsies with chronic rejection, M% was nearly twice as high as in contemporaneous biopsies showing mild or no rejection. Monitoring of enzymatic adaptation from endomyocardial biopsies may be of clinical interest.

Adolescent↗

PubMed1991

[Application of differential derivative spectrophotometry to the determination of total chlorogenic acid in Lonicera japonica Thunb. and yinqiao jiedu pian].

The total chlorogenic acid in Lonicera japonica and yinqiao jiedu pian was determined by differential derivative spectrophotometry in this paper. Quantitative analysis of this component in eight mixtures of medicinal herbs can be done without any separation. The average recovery of total chlorogenic acid is 100.40 +/- 1.82% (CV). The method features good reproducibility, favorable stability and high sensitivity.

Chlorogenic Acid↗

PubMed1990

Immunoaffinity purification and functional characterization of interphase and meiotic Drosophila nuclear lamin isoforms.

Three isoforms of a single nuclear lamin have been identified in Drosophila. Two, lamins Dm1 and Dm2, are present during interphase and are apparently in equilibrium with each other in vivo. The third, lamin Dmmit, is found in cells that have undergone nuclear envelope breakdown, either during meiosis or mitosis. All three isoforms were purified under nondenaturing conditions using a novel technique of immunoaffinity chromatography and their in vitro activities were examined. Interphase lamins Dm1 and Dm2 can assemble into filaments at physiologic ionic strength; assembly is reversible upon addition of concentrated NaCl. Negative staining of filaments formed in vitro shows long, unbranched bundles approximately 20 nm in diameter. Addition of specific antilamin antibodies blocks in vitro assembly completely. In contrast with lamins Dm1 and Dm2, lamin Dmmit remains soluble at physiologic ionic strength. These observations are consistent with the notion that lamina disassembly in vivo is due, at least in part, to changes in properties of the lamins themselves.

Animals↗

PubMed1990

In vitro dissolution and in vivo bioavailability of commercial levothyroxine sodium tablets in the hypothyroid dog model.

The objective of this study was to determine whether a correlation exists between the rate of in vitro dissolution and bioavailability of levothyroxine sodium (T4) tablets. Dissolution versus time profiles for Synthroid, the Flint brand of levothyroxine sodium, and two competitors' tablets (brands A and B) were generated using an official dissolution apparatus (USP), and 0.05 M phosphate buffer (pH 7.4) as the medium. These tablets were also utilized in single-dose crossover bioavailability studies in the hypothyroid dog model (n = 6). The average areas under the serum T4 concentration versus time curve from 0 to 8 h (AUC) for Synthroid, brand A, and brand B were 8.22, 6.32, and 8.70 ng-h/mL per dose (micrograms per kg body weight), respectively. Respective peak serum concentrations (Cmax) for each tablet formulation were 1.26, 1.07, and 1.36 ng/mL per dose. The corresponding dissolution rates, expressed as t50%, were 20.5, 3.06, and 14.1 min, respectively. Data analysis indicated no correlation between dissolution kinetic parameters and the bioavailability parameters AUC and Cmax. However, a linear relationship was observed between dissolution kinetics and both the time to reach maximal serum concentration (tmax) and the observed absorption rate constant (ka).

Animals↗

PubMed1990

Medium-chain-triglyceride lipid emulsion: metabolism and tissue distribution.

The utilization and distribution of radioactively labeled lipid emulsions were evaluated in Sprague-Dawley rats. Animals received one of three lipid emulsions. Group 1 received [14C]medium-chain-triglyceride (MCT) lipid emulsion, group 2 received a 75%:25% (vol:vol) admixture of [14C]MCT: unlabeled long-chain-triglyceride (LCT) lipid emulsion, and group 3 received only [14C]LCT. The radioactive dose appearing in expired carbon dioxide and various body tissues was monitored over a 24-h period. Results indicate that MCT is oxidized more rapidly and completely than in LCT; approximately 90% of the MCT is converted to carbon dioxide with in 24 h compared with 45% for LCT. When MCT and LCT are administered together, the metabolism of MCT is slowed but remains more rapid than that of LCT. Removal of MCT from the blood was more rapid than was removal of LCT, and tissue radioactivity was lower.

Animals↗

PubMed1990

Gastric secretion pH measurement: what you see is not what you get!

We evaluated the accuracy of gastric secretion pH measurements as performed in three ICUs. The pH of 275 samples was measured with pH paper using established techniques. The pH of 85 additional samples was determined with a hand-held pH meter. All specimens also were measured using a research laboratory pH meter to learn the true pH. Analyses included mean and SD of the difference between the two measurements, the correlation coefficient (r value), and the concordance correlation coefficient. The pH meter values disagreed significantly with pH paper measurements. Measurements of gastric secretion pH with pH indicator paper do not guide therapy reliably. Inaccurate values derived from pH paper measurements could have resulted in inappropriate treatment in 28% of the samples tested. A portable, battery-powered pH meter accurately reproduced laboratory pH meter measurements and is a reasonable device for clinical use.

Gastric Acidity Determination↗

PubMed1990

Comparison of 18O exchange and pH stop-flow assays for carbonic anhydrase.

The hydration velocity of CO2 (0.002 M) catalyzed by bovine carbonic anhydrase (BCA) was measured at 25 degrees C and pH 7.4 by three different techniques: two initial-rate (steady-state) stop-flow methods, one using a glass pH electrode (in Hannover, method 1) and one using spectrophotometric measurements of a pH indicator (in Philadelphia, method 2), and an exchange method in which the disappearance of C18O16O from a bicarbonate solution was determined at equilibrium (in Philadelphia, method 3). The Michaelis-Menten constant (Km) and the inhibition constants for chloride (Ki,Cl) and ethoxzolamide (Ki,ez) were the same for methods 1, 2, and 3. The turnover numbers were 270,000, 400,000, and 555,000 s-1 by methods 1, 2, and 3, respectively. Values for CO2 hydration velocity measured by methods 2 and 3 on the same solution of BCA at the same time were the same. Km, maximal reaction velocity (Vmax), Ki,ez, and Ki,Cl obtained from normal human hemolysate at 37 degrees C and pH 7.2 by methods 2 and 3 were the same. Km and Vmax of the carbonic anhydrase isozyme CA III of homogenate from rabbit soleus were also identical by methods 1 and 3. According to Michaelis-Menten theory, the values of Km and Vmax obtained by method 3 should have been significantly smaller than those obtained by methods 1 and 2. We conclude that the catalytic step itself is apparently not rate limiting under physiological conditions and that method 3 can be used to obtain Michaelis-Menten characteristics of carbonic anhydrase.

Animals↗

PubMed1990

Myoglobin content and citrate synthase activity in different parts of the normal human heart.

Myoglobin (Mb) content and citrate synthase (CS) activity were determined in myocardial samples from nine human brain-dead organ donors with normal hearts. Six regions of each heart were analyzed: right and left atria, right ventricle, left ventricular subepicardium, subendocardium, and anterior papillary muscle. The Mb content was similar, whereas the CS activity was higher in the left than in the right heart at both atrial and ventricular levels. Mb content and CS activity were higher in ventricles than in atria. The subendocardial layer and papillary muscle of the left ventricle had a higher Mb content than the subepicardial layer, whereas CS activity was similar in these three locations. The results suggested a closer relationship between CS activity (oxidative potential) and work load than between Mb content and work load. Mb content may, instead, be related to intramuscular oxygen tension (PO2) on the basis of a comparison between our Mb data and those of others on regional variations in myocardial PO2.

Adolescent↗

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↗