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Biomedical subjects

J Lin

Publications and source records attributed to J Lin.

At least 667 records · Page 37Linked to original sources
PubMed1992

The YAG laser used in micromanipulation to transect the zona pellucida of hamster oocytes.

PROBLEM: Since there has been no reported use of the YAG laser to micromanipulate oocytes, our purpose was to study whether (1) a YAG laser could be used to open the zona pellucida of hamster oocytes; (2) human sperm could reach the ooplasm and (3) under sperm penetration assay conditions, sperm would bind and penetrate the ooplasm. RESULTS: A YAG 100 laser was used at 10 W and 0.4-sec pulse width to open eight of eight ooplasm oocytes. The opening in the zonae was 0.25 to 1.0 rad (10 to 40 microns). For the initial eight oocytes and two parallel controls, the coarse appearance of the ooplasm was unchanged after 3 days. Next, in 11 of 12 manipulated oocytes, the sperm clustered at the opening of the zona. When 16 more oocytes were opened and exposed to sperm in sperm penetration assay conditions, each ooplasm bound sperm. There was no penetration noted. Each manipulation time was < 1 min. To clarify the laser effect, oocytes were exposed to laser energy then utilized as the interactive surface in the sperm penetration assay. It was found that only 20% bound sperm with no penetration. CONCLUSION: While the time factor compares favourably with other methods of zona opening, further study needs to be performed to minimize effect to the exposed oocyte.

Animals↗
PubMed1992

Renal aspergilloma: an unusual cause of infection in a patient with the acquired immunodeficiency syndrome.

The case of a 36-year-old man with the acquired immunodeficiency syndrome (AIDS) and a renal aspergilloma is reported. Aspergillus infections are uncommon in patients with AIDS. Isolated renal aspergillomas have rarely been reported in the non-AIDS population (14 cases) and have never been reported in a patient with AIDS. The patient we describe was clinically symptomatic and initially treated medically, but he did not respond to intravenous amphotericin and oral itraconazole. He eventually required nephrectomy; however, there was local recurrence of the aspergilloma postoperatively. We comment on some issues in the spectrum of Aspergillus infections in AIDS and review the literature on the manifestations and treatment of renal aspergillomas.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Characterization of the heat shock response in Brucella abortus and isolation of the genes encoding the GroE heat shock proteins.

In an effort to define the heat shock response in the bovine intracellular pathogen Brucella abortus, a rough variant lacking extensive lipopolysaccharide was pulse-labeled with [35S]methionine following exposure to elevated temperatures. The major heat shock proteins observed following sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography migrate at 70, 62, 18, and 10 kDa. The maximum response was observed between 42 and 46 degrees C and within 2 to 3 h of the shif in temperature and varied slightly for the different proteins. Accumulation of the 62-kDa heat shock protein (62-kDa Hsp) was observed to continue for up to 5 h following the shift in temperature. In an effort to better define the heat shock response and its potential relationship with protective immunity, genes encoding the major heat shock proteins were isolated from recombinant libraries constructed from B. abortus S19 and S2308 and sequenced. The 62-kDa Hsp shares more than 60% amino acid homology with members of the GroEL family and is immunoprecipitated with polyclonal antibodies to Escherichia coli GroEL and monoclonal antibodies to mycobacterial Hsp 65. Western blot (immunoblot) analysis with pooled sera from vaccinated and infected cattle revealed that the 62-kDa Hsp is a predominantly recognized antigen. The roles of these gene products during environmental stress and in protective immunity against brucellosis are under investigation.

Amino Acid Sequence↗
PubMed1992

Analysis of mutations in trfA, the replication initiation gene of the broad-host-range plasmid RK2.

Plasmids with mutations in trfA, the gene encoding the replication initiation protein of the broad-host-range plasmid RK2, were isolated and characterized. Mutants identified from a nitrosoguanidine bank were defective in supporting the replication of a wild-type RK2 origin in Escherichia coli. Most of the mutations were clustered in a region of trfA corresponding to the carboxy-terminal quarter of the TrfA protein. 5' and 3' deletion mutants of trfA were also constructed. A C-terminal deletion of three amino acids of the Tr A protein was completely nonfunctional for RK2 replication. However, a deletion of 25 amino acids from the start of the 33-kDa TrfA protein was still competent for replication. Further characterization of the point and deletion trfA mutants in vivo revealed that a subset was capable of supporting RK2 replication in other gram-negative bacteria, including Pseudomonas putida, Agrobacterium tumefaciens, and Azotobacter vinelandii. Selected mutant TrfA proteins were partially purified and characterized in vitro. Velocity sedimentation analysis of these partially purified TrfA proteins indicated that the wild-type protein and all mutant TrfA proteins examined exist as dimers in solution. Results from in vitro replication assays corroborated the experimental findings in vivo. Gel retardation results clearly indicated that the point mutant TrfA-33:151S, which was completely defective in replication of an RK2 origin in all of the bacterial hosts tested in vivo, and a carboxy-terminal deletion mutant, TrfA-33:C delta 305, were not able to bind iterons in vitro. In addition to the partially defective or could not be distinguished from the wild-type protein in binding to the origin region. The mutant proteins with apparently normal DNA-binding activity in vitro either were inactive in all four gram-negative bacteria tested or exhibited differences in functionality depending on the host organism. These mutant TrfA proteins may be altered in the ability to interact with the replication proteins of the specific host bacterium.

Agrobacterium tumefaciens↗
PubMed1992

Spectrum of monoclonal antibodies to coxsackievirus B-3 includes type- and group-specific antibodies.

Fifteen monoclonal antibodies (MAbs) made to coxsackievirus B-3 were tested against a panel of enteroviruses by indirect immunofluorescence. The MAbs included seven which reacted with coxsackievirus B-3 only, five which reacted with more than one enterovirus included in the panel, one which reacted with broad enteroviral specificity and did not react with any heterologous virus (group specific), and two which reacted with all enteroviruses tested and at least one heterologous virus. The group-specific MAb identified 44 of 45 clinical isolates as enteroviruses, while the two broadly reactive MAbs reacted with all 45 of the clinical isolates. These MAbs are potentially important diagnostic reagents for grouping and typing enteroviruses by indirect immunofluorescence.

Antibodies, Monoclonal↗
PubMed1992

Apolipoprotein(a) gene accounts for greater than 90% of the variation in plasma lipoprotein(a) concentrations.

Plasma lipoprotein(a) [Lp(a)], a low density lipoprotein particle with an attached apolipoprotein(a) [apo(a)], varies widely in concentration between individuals. These concentration differences are heritable and inversely related to the number of kringle 4 repeats in the apo(a) gene. To define the genetic determinants of plasma Lp(a) levels, plasma Lp(a) concentrations and apo(a) genotypes were examined in 48 nuclear Caucasian families. Apo(a) genotypes were determined using a newly developed pulsed-field gel electrophoresis method which distinguished 19 different genotypes at the apo(a) locus. The apo(a) gene itself was found to account for virtually all the genetic variability in plasma Lp(a) levels. This conclusion was reached by analyzing plasma Lp(a) levels in siblings who shared zero, one, or two apo(a) genes that were identical by descent (ibd). Siblings with both apo(a) alleles ibd (n = 72) have strikingly similar plasma Lp(a) levels (r = 0.95), whereas those who shared no apo(a) alleles (n = 52), had dissimilar concentrations (r = -0.23). The apo(a) gene was estimated to be responsible for 91% of the variance of plasma Lp(a) concentration. The number of kringle 4 repeats in the apo(a) gene accounted for 69% of the variation, and yet to be defined cis-acting sequences at the apo(a) locus accounted for the remaining 22% of the inter-individual variation in plasma Lp(a) levels. During the course of these studies we observed the de novo generation of a new apo(a) allele, an event that occurred once in 376 meioses.

Alleles↗
PubMed1992

Growth inhibition and modulation of antigenic phenotype in human melanoma and glioblastoma multiforme cells by caffeic acid phenethyl ester (CAPE)

The active component of the honeybee hive product propolis, caffeic acid phenethyl ester (CAPE), has been shown to display increased toxicity toward various oncogene-transformed cell lines in comparison with their untransformed counterparts (Su et al., 4: 231-242, 1991). This observation provides support for the concept that it is the transformed phenotype which is specifically sensitive to CAPE. In the present study, we have determined the effect of CAPE on the growth and antigenic phenotype of a human melanoma cell line, HO-1, and a human glioblastoma multiforme cell line, GBM-18. For comparison, we have also tested the effects of mezerein (MEZ), mycophenolic acid (MPA) and retinoic acid (RA), which can differentially modulate growth, differentiation and the antigenic phenotype in these human tumor cell lines. Growth of both cell lines was suppressed by CAPE in a dose-dependent fashion, with HO-1 cells being more sensitive than GBM-18 cells. The antiproliferative effect of CAPE was enhanced in both cell types if CAPE and MEZ were used in combination. Growth suppression was associated with morphological changes in H0-1 cells, suggesting induction of a more differentiated phenotype. CAPE also differentially modulated the expression of several antigens on the surface of the two tumor cell lines. These results suggest a potential role for CAPE as an antitumor agent, an antigenic modulating agent and possibly a differentiation inducing agent.

Antigens, Neoplasm↗
PubMed1992

[Effect of the root of Polygonum multiflorum Thunb. and its processed products on fat accumulation in the liver of mice].

Experiments have shown that the root of Polygonum multiflorum exhibits inhibitory effect on triglyceride (TG) accumulation in the liver of mice induced by CCl4, cortisone acetate and thioacetamide (TAA). Its processed products (I, II) were found to be effective in lowering the accumulated TG induced by cortisone acetate. The root of Polygonum multiflorum and its processed products also reduced the enlargement of liver by CCl4.

Animals↗
PubMed1992

Estimation for model parameters of batch fermentation kinetics.

Based on the widely accepted mathematical model of fermentation kinetics, an analytical solution is deduced in this paper. To describe the feature of batch fermentation, the parameters of the fermentation kinetics in the analytical solution (i.e., mumax, Ks, beta, YG, YP, and m) are estimated at one strike with POWELL optimization algorithm coded in FORTRAN-77. The experimental data in the example is quoted from a batch lysine fermentation process using Corynebacterium glutamicum. The result shows that: 1) the calculated values of the mathematical model agree very well with the experimental data; 2) the synthesis rate of lysine depends on both the growth rate and the concentration of the biomass.

Algorithms↗
PubMed1992

[Refractive error and amblyopia in children].

The refractive status of 3,099 children was analyzed. The result showed that the incidence and degree of hyperopia decreased gradually and those of myopia increased along with the growing up of children in ametropia. In binocular refractive amblyopia, high and medium hyperopia and myopia in severe and medium amblyopia were significantly more than those in mild amblyopia. In monocular refractive amblyopia, high and medium hyperopia and high myopia in the amblyopic eyes were more than those in the nonamblyopic eyes. The refractive status of binocular esotropic amblyopia had no significant difference in various ages and degrees of amblyopia. There was also no significant difference between the refractive status of the amblyopic and nonamblyopic eyes in monocular esotropic amblyopia. It was considered that refractive amblyopia was closely related to high ametropia and the deviation of the eye might be the main cause of strabismic amblyopia.

Adolescent↗
PubMed1992

[Immunohistochemical study of transferrin receptor expression in hepatocellular carcinoma].

By means of immunohistochemical technique ABC, using monoclonal anti-transferrin receptor (TFR) antibodies WuT9 and OKT9, TFR expression in 30 cases of hepatocellular carcinoma (HCC) and in 6 cases of organs and tissues of normal human bodies was studied. It was revealed that large amount of TFR were expressed in liver cancer cells, but not in the surrounding mesenchymal cells as demonstrated by intense immunostaining in cancer nests, and even not in the surrounding mesenchyma of those HCC patients with negative AFP in their serum. In normal human body, only small amount of TFR in limited sites was found without free antigen in blood stream. Thus, it followed that TFR as a structural antigen of HCC was expressed with higher relative specificity than AFP, and TFR may be considered a tumor marker and therapeutic target of HCC.

Antibodies, Monoclonal↗
PubMed1992

[Ageing suppresses the enhancement of T cell mitogenesis by opioid peptides and enkephalins increase phagocytosis of murines macrophage].

The opioid peptides methionine enkephalin (M-ENK) and beta-endorphin (beta-END) (1 x 10(-5)-1 x 10(-11) mg/ml) were investigated for their effect on the PHA (1:500, 1:750 or 1:1000) induced proliferative response of old and young Wistar rat splenic lymphocytes in vitro. The different effects in young and old rats on proliferative response to PHA were determined. The results showed that MENK and beta-END significantly enhanced the proliferative response to PHA in young rats, while enhancement by M-ENK and beta-endorphin (PHA 1:750, 1:1000) was not observed in old rats. The PHA-induced proliferative response was 30%-40% lower in old rats than in young rats. Our results suggest an altered response to neuro-immunomodulation with age. The in vitro effect of ENKs on phagocytosis was also studied. The results indicated that LENK (10(-4)-10(-6) mg/ml) and MENK (10(-2)-10(-4) mg/ml) could stimulate the phagocytosis of peritoneal macrophages from Balb/c mice.

Aging↗
PubMed1992

[The influence of different acupuncture manipulations on the plethysmogram of the patient with kidney deficiency].

In order to prove the specific property between the tonifying manipulation (TM) and reducing manipulation (RM), and search further for the key in improving the effect of manipulation, the influence of to on two different manipulations. The plethysmogram in the same body-condition (kidney-deficiency) One was TM with slow-trusting and quick lefting; the other was RM with the converse movement. Randomized block design, cross-over design and single-blind design were used. The result showed that the TM increased the amplitude of the plethysmogram obviously, whereas the RM had no significant influence on it. There was significant difference not only between the TM group and the central group, but also between the TM group and RM group (P less than 0.01 or P less than 0.05). The difference between the RM group and the control group was not significant (P greater than 0.05). Meanwhile, it was recommended that "mind concentration" on acupuncture manipulation is important. In conclusion, the experiment demonstrated the experimental evidence for explaining the mechanism of TM and RM. It was suggested that acupuncture manipulations are worthy to pay attention so as to improve clinical effect.

Acupuncture Therapy↗
PubMed1992

Enzymes of the thymidylate cycle as targets for chemotherapeutic agents: mechanisms of resistance.

This brief review should serve to indicate that it is possible to assess tumor sensitivity to antifolates using fresh human tissue in short-term culture. The assays described differ from general assays of tumor sensitivity, such as the clonogenic assay or assays that measure 3H-thymidine incorporation as an indicator of cell viability (32-34), in that the effect of a drug on a human specific target (dihydrofolate reductase) is measured. These specific assays also may prove to be extremely useful in the detection of acquired drug resistance and for new analog drug development. In a general sense, this type of assay may eventually also be useful for guiding and selecting treatment for individual patients with other drugs with known mechanisms of action. Knowledge of the basis of tumor resistance is essential to develop new approaches to treatment, such as the use of other folate analogs that may still be effective, and to devise ways in which to selectively inhibit tumor cell growth using new analogs (trimetrexate) and leucovorin.

Antimetabolites, Antineoplastic↗
PubMed1991

Relative efficiencies of the maximum-parsimony and distance-matrix methods of phylogeny construction for restriction data.

The relative efficiencies of the maximum-parsimony (MP), UPGMA, and neighbor-joining (NJ) methods in obtaining the correct tree (topology) for restriction-site and restriction-fragment data were studied by computer simulation. In this simulation, six DNA sequences of 16,000 nucleotides were assumed to evolve following a given model tree. The recognition sequences of 20 different six-base restriction enzymes were used to identify the restriction sites of the DNA sequences generated. The restriction-site data and restriction-fragment data thus obtained were used to reconstruct a phylogenetic tree, and the tree obtained was compared with the model tree. This process was repeated 300 times. The results obtained indicate that when the rate of nucleotide substitution is constant the probability of obtaining the correct tree (Pc) is generally higher in the NJ method than in the MP method. However, if we use the average topological deviation from the model tree (dT) as the criterion of comparison, the NJ and MP methods are nearly equally efficient. When the rate of nucleotide substitution varies with evolutionary lineage, the NJ method is better than the MP method, whether Pc or dT is used as the criterion of comparison. With 500 nucleotides and when the number of nucleotide substitutions per site was very small, restriction-site data were, contrary to our expectation, more useful than sequence data. Restriction-fragment data were less useful than restriction-site data, except when the sequence divergence was very small. UPGMA seems to be useful only when the rate of nucleotide substitution is constant and sequence divergence is high.

Computer Simulation↗
PubMed1991

Bovine brain microsomal CDP-diacylglycerol synthetase: solubilization and properties.

CDP-diacylglycerol(DAG) synthetase (EC 2.7.7.41) has been solubilized from bovine brain microsomes by the detergent CHAPS (3-[(3-cholamidopropyl) dimethylammonio] -1-propanesulfonate). Optimal solubilization with 1.5% CHAPS yielded 55-60% of the synthetase activity. The effect of CHAPS on the enzyme was biphasic inhibiting at 0.3% and giving maximal activity at 0.5% (the concentration used for all assays). The solubilized, but not the microsomal enzyme is activated by phosphatidylcholine (PC) and strongly inhibited by cardiolipin and lysoPC. Strong inhibition by N-ethylmaleimide, 5,5'-dithio-bis (2-nitrobenzoic acid) and p-chloromercuribenzoate supported a sulfhydryl requirement for the enzyme. Phosphatidic acid (PA) from egg lecithin and 1-stearoyl,2-arachidonoyl PA were preferred substrates for the microsomal synthetase. Solubilized synthetase showed selectivity for the latter PA which is consistent with this enzyme functioning to help form the preponderant 1-stearoyl,2-arachidonoyl species of phosphatidylinositol. Further attempts to purify the synthetase were unsuccessful. All findings suggested the enzyme exists as an unstable complex.

Animals↗
PubMed1991

[A study on aetiological factors of primary hepato-carcinoma in Tianjin China].

In order to investigate the possible risk factors of primary hepato-carcinoma (PHC) in Tianjin, 122 clinical diagnosed PHC patients and matched hospital controls were interviewed and 99 pairs of their blood samples were examined for HBV. The findings confirmed the strong association between HBV infection and PHC. The individual's immune state during HBV infection might be an important factor for PHC development. Histories of hepatitis and cirrhosis and family history of PHC were risk factors of PHC. Cigarette smoking might have association with PHC. Smoking for more the years of, the higher the risk of PHC. The present study did not find association between PHC and drinking water, dietary habits, alcohol consumption, histories of blood transfusion and injection, exposure to pesticides and poison.

Adolescent↗