Biomedical subjects

D Y Liu

Publications and source records attributed to D Y Liu.

133 records · Page 8Linked to original sources

PubMed1980

Effects of human complement component 1 inactivator on neutrophil chemotaxis and chemotactic deactivation.

This study was undertaken to ascertain the relationship between complement-derived chemotactic factors and complement component 1 inactivator (C1INA) enhancement of neutrophil chemotaxis. Studies were also designed to determine whether the C1s- reactive or binding site on C1INA was functional in altering chemotactic responsiveness of neutrophilic leukocyes. Chemotaxis was assessed by determining cell migration in micropore filters. C1INA was found to enhance the chemotactic response to zymosan-activated plasma, C5a, and N-formyl-L-methionyl-L-phenylalanine and to bring the response of chemotactically deactivated cells to normal. In contrast, C1INA inhibited the chemotactic response to trypsin and EAC4oxy2-activated C3. Complexes of C1INA and C1s- failed to mediate the usual C1INA-enhanced response. Artificially produced C5-deficient plasma, when treated with zymosan, failed to support chemotaxis or to produce chemotactic deactivation. C1INA was without effect when this activated plasma was used as a source of chemotactic factors. We conclude from these data that C1INA enhancement of neutrophil chemotaxis to activated plasma is associated with C5-derived chemotactic fragments. The effects of C1INA are apparently related to the C1s- reactive or binding site(s) on the C1INA molecule. We suggest that C1INA may play a homeostatic role in neutrophil chemotaxis.

Blood Physiological Phenomena↗

PubMed1980

Role of sialic acid in the macrophage glycolipid receptor for MIF.

Acidic glycolipids from guinea pig macrophages enhance the response of macrophages to migration inhibitory factor (MIF), suggesting a role of glycolipid receptors for this lymphocyte mediator. Neuraminidase treatment of these glycolipids results in the loss of their biologic activity. This activity remains intact after incubation of the glycolipids with beta-galactosidase. In order to investigate whether sialic acid is essential for the macrophage's response to MIF, macrophages were incubated with neuraminidase. Neuraminidase treatment of peritoneal exudate cells results in the abrogation of macrophage responsiveness to MIF. Other exoglycosidases such as beta-galactosidase and beta-glucosidase had no effect upon the macrophage response. The effect of neuraminidase was found to be reversible within 18 hr. These experiments suggest that macrophage glycolipids containing sialic acid are components of the macrophage receptor for MIF.

Animals↗

PubMedDate not supplied

Correlation between defective motility (asthenospermia) and ATP reactivation of demembranated human spermatozoa.

Human spermatozoa treated with 0.05% Triton X-100 to remove the cell membranes became immotile but flagellar movement was reinitiated by addition of 0.06 to 1 mM adenosine triphosphate (ATP). The percentage of spermatozoa showing flagellar movement 2 minutes after addition of 1 mM ATP from men with idiopathic asthenospermia (mean +/- SD, 34 +/- 15%), oligozoospermia (17 +/- 21%), sperm autoimmunity (17 +/- 12%), vasoepididymostomy (20 +/- 22%), or idiopathic zero motility (0%) was significantly lower than with spermatozoa from normal men (54 +/- 12%). The percentage of reactivated spermatozoa was correlated with the proportion of live cells (Eosin Y stain, r = 0.602, P less than 0.001), percentage of motile cells (r = 0.761, P less than 0.001), and motility index (r = 0.759, P less than 0.001) in the same semen samples. When expressed relative to initial sperm motility, the proportion reactivated was similar for idiopathic asthenospermia (85%) and normospermia (82%). Thus, failure to produce ATP does not appear to be a frequent cause of low sperm motility in man.

Adenosine Triphosphate↗

PubMedDate not supplied

Metabolism of 9-(2-chlorobenzyl)-, 9-(2-methylbenzyl)- and 9-(2-methoxybenzyl)-adenines by hamster hepatic microsomes.

It was previously found that 9-benzyladenine (BA) was extensively N1-oxidised by animal hepatic microsomes; further, mononitrosubstitution in the phenyl moiety of BA significantly modified the N1-oxidation rates of the corresponding substrates. In order to establish whether the electronic nature or a steric effect of the substituents in the phenyl moiety is the reason for the modification of N1-oxidation rate, the metabolism of some 2'-substituted 9-benzyladenines, i.e. 9-(2-chlorobenzyl)adenine (2CBA), 9-(2-methyl-benzyl)adenine (2MBA) and 9-(2-methoxybenzyl)adenine (2MOBA), by hamster hepatic microsomes was studied. It was found that the N1-oxide was still the major metabolite for 2CBA. However, only minor amounts of N1-oxides were formed during microsomal incubation with 2MBA and 2MOBA. On the other hand, in spite of the higher N1-oxidation rate of 2CBA, its total biotransformation rate was slightly lower than the other two substrates. Like other 9-aralkyladenines previously studied, dealkylation occurred for all three substrates. It was also found that another two metabolites formed in significant amounts in the incubates from both 2MBA and 2MOBA. These metabolites were not fully characterised and their structures unknown.

Adenine↗

PubMedDate not supplied

Studies on the relationship between in vitro metabolism and certain physicochemical characteristics of some 9-alkyl-/9-aralkyl adenines.

Previous studies demonstrated that biological N1-oxidation occurred for some 9-alkyl-/9-aralkyladenines, but not for others, when mammalian hepatic microsomal incubates were used as enzyme source. In order to understand the mechanisms controlling the metabolic fate of these compounds, the relationship between N1-oxidation and certain physicochemical characteristics of these substrates was studied. It was found that there was no marked link between N1-oxidation and the computer predicted pKa values of the substances studied. However, a computer predicted LogP value in the range 1.3-4 seems to be the most favourable for N1-oxidation. The 1H-NMR and 13C-NMR spectroscopic characteristics of the substrates, which reflect certain electronic characteristics of the purine moiety, also showed a correlation with their N1-oxidation. The electronic effects of the substrates in relation to their metabolism was investigated using computer modelling techniques; the results showed that different substituents at the 9-position of adenine may modify the electronic characteristics of the purine moiety thus affecting their metabolism. The conformation of the substrates may also be an important controlling factor for their N1-oxidative metabolism.

Adenine↗

PubMedDate not supplied

Immunoinfertility: a case study with implications for immunocontraception.

A detailed case history was compiled on a couple who have had primary infertility for more than 20 years. The history and further laboratory investigations indicated that the infertility was caused by high-titre sperm antibodies in the female. The antibodies blocked sperm-zona binding and reacted with a prominent band at 65 kD in Western blots. Preliminary studies indicate that a subset of the patient's antibodies are specific for a unique protein sequence expressed by a cDNA testis library. This antigen may have potential for immunocontraceptive vaccine development.

Antibodies↗

PubMedDate not supplied

Relationship between sperm motility assessed with the Hamilton-Thorn motility analyzer and fertilization rates in vitro.

To determine which sperm movement characteristics are related to in vitro fertilization rates, semen and swim-up preparations used for in vitro fertilization in 108 patients were assessed using the Hamilton-Thorn HTM-2030 Motility Analyzer (HTMA) and other sperm tests. There were highly significant correlations between manual and HTMA results for sperm concentration (Spearman r = 0.881; P less than 0.001) and the percentage of motile spermatozoa (Spearman r = 0.580; P less than 0.001). The percentage of motile spermatozoa with average path velocities greater than 10 microns/s and greater than 20 microns/s, straight line and curvilinear velocity, linearity (straight line velocity vs curvilinear velocity), amplitude of lateral head displacement, and beat-cross frequency were significantly higher in the insemination medium after selection of motile spermatozoa by the swim-up technique than in the semen. Linearity (P less than 0.01), the percentage of morphologically normal spermatozoa (P less than 0.05) and straight line velocity (P less than 0.05) in semen, and the percentage of motile spermatozoa with average path velocities greater than 10 microns/s in both semen (P less than 0.05) and insemination medium (P less than 0.05) were significantly correlated with in vitro fertilization rate when examined by a nonparametric (Spearman) test. With logistic regression analysis of all data, only the diagnoses of male infertility and tubal disease, linearity in semen, and the percentage of motile spermatozoa with average path velocities between 10 and 20 microns/s in insemination medium were significantly related to in vitro fertilization rates.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗