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Biomedical subjects

T Huang

Publications and source records attributed to T Huang.

At least 127 records · Page 7Linked to original sources
PubMed1996

The effect of peritoneal fluid from patients with endometriosis on human sperm function in vitro.

OBJECTIVE: Our purpose was to evaluate the effect of peritoneal fluid from women with endometriosis on sperm motility and function in an in vitro model. STUDY DESIGN: Peritoneal fluid was collected at laparoscopy from patients with and without endometriosis. Human donor sperm was diluted with this fluid, and its effect on sperm function and motility was measured was measured with the zona-free hamster egg sperm penetration assay and computer-assisted semen analysis. RESULTS: The mean number of eggs penetrated by the sperm mixed with peritoneal fluid from patients with endometriosis was significantly fewer than the number penetrated by the sperm mixed with fluid from control patients (22.9 +/- 5.31 vs 44.4 +/- 4.96, p < 0.01, Student t test, n = 20). When evaluated by computer-assisted semen analysis, sperm mixed with peritoneal fluid from patients with endometriosis showed a significant decrease in mean swimming velocity compared with sperm mixed with peritoneal fluid from control patients (54.0 +/- 1.77 vs 59.2 +/- 1.05, p = 0.02, Student t test, n = 20). A significant increase in the fraction of sperm swimming at slower velocities was also found. A trend toward a positive correlation between eggs penetrated and sperm velocity was seen, but statistical significance was not achieved (correlation coefficient 0.4392, p = 0.053, n = 20). CONCLUSION: These data suggest that substances found in the peritoneal fluid of patients with endometriosis could contribute to infertility through impairment of both sperm function and motion kinematics.

Adult↗
PubMed1996

Potent and selective inhibition of gene expression by an antisense heptanucleotide.

Factors that govern the specificity of an antisense oligonucleotide (ON) for its target RNA include accessibility of the targeted RNA to ON binding, stability of ON/RNA complexes in cells, and susceptibility of the ON/RNA complex to RNase H cleavage. ON specificity is generally proposed to be dependent on its length. To date, virtually all previous antisense experiments have used 12-25 nt-long ONs. We explored the antisense activity and specificity of short (7 and 8 nt) ONs modified with C-5 propyne pyrimidines and phosphorothioate internucleotide linkages. Gene-selective, mismatch sensitive, and RNase H-dependent inhibition was observed for a heptanucleotide ON. We demonstrated that the flanking sequences of the target RNA are a major determinant of specificity. The use of shorter ONs as antisense agents has the distinct advantage of simplified synthesis. These results may lead to a general, cost-effective solution to the development of antisense ONs as therapeutic agents.

Animals↗
PubMed1996

Reduction of the allergenicity of soybean by treatment with proteases.

Soybeans were treated with proteases to reduce allergenicity. By immunoblotting with a monoclonal antibody against a major soybean allergen (Gly m Bd 30K), two of eight proteases so far tested were selected to achieve a reduction in allergenicity. Both antigenicity to the monoclonal antibody and allergenicity to the sera from soybean-sensitive patients proved to be markedly reduced by processing with either protease. Thus, soybeans treated with an appropriate protease may possibly be supplied as a hypoallergenic foodstuff for patients.

Adult↗
PubMed1995

Mechanism for the coupling of ATP hydrolysis to the conversion of 5-formyltetrahydrofolate to 5,10-methenyltetrahydrofolate.

5,10-Methenyltetrahydrofolate synthetase catalyzes the irreversible conversion of 5-formyl-tetrahydropteroylpolyglutamates (5-CHO-H4PteGlu(n)) to 5,10-methenyltetrahydropteroylpolyglutamates (5, 10-CH(+)-H4PteGlu(n)). The equilibrium of the nonenzymatic reaction, which equilibrates slowly in the absence of enzyme, greatly favors 5-CHO-H4PteGlu(n). The enzyme couples the reaction to the hydrolysis of ATP shifting the equilibrium to favor 5,10-CH(+)-H4PteGlu(n). Substrate-dependent non-equilibrium isotope exchange of [3H]ADP into ATP was observed, suggesting the formation of a phosphorylated intermediate of 5-CHO-H4PteGlu(n) during the enzyme-catalyzed reaction. The competitive inhibitor 5-formyltetrahydrohomofolate also supported the ADP to ATP exchange, suggesting that this molecule could also form a phosphorylated intermediate. The initial rates of the ADP-ATP exchange with saturating ADP were about 70 s-1 for both compounds, while the kcat values for product formation were 5 s-1 for 5-CHO-H4PteGlu(n) and 0.005 s-1 for 5-formyltetrahydrohomofolate. Starting with 5(-)[18O]CHO-H4PteGlu(n), it was shown by 31P NMR that the formyl oxygen of the substrate was transferred to the product phosphate during the reaction. This further supports the existence of a phosphorylated intermediate. The formyl group of 5-CHO-H4PteGlu(n) is known to be an equilibrium mixture of two rotamers. Stopped-flow analysis of the enzymatic reaction showed that only one of the rotamers serves as a substrate for the enzyme.

Adenosine Triphosphate↗
PubMed1995

Detection of basal acetylcholine in rat brain microdialysate.

A liquid chromatography-electrochemistry (LC-EC) method is described for the determination of basal acetylcholine (ACh) in microdialysate from the striatum of freely moving rats. This method is based on the separation of ACh and choline (Ch) by microbore liquid chromatography followed by passage of the effluent through a post-column immobilized enzyme reactor (IMER), containing acetylcholinesterase (AChE) and choline oxidase (ChO), and then the electrochemical detection of the hydrogen peroxide produced. Instead of the conventional platinum electrode generally used for the anodic detection of hydrogen peroxide, a peroxidase-redox polymer modified glassy carbon electrode operated at + 100 mV vs. Ag/AgCl has been used to detect the reduction of hydrogen peroxide. With this method, a detection limit of 10 fmol (injected) for ACh (S/N = 3:1) was obtained and the basal ACh concentration in striatal microdialysate was determined without using esterase inhibitors.

Acetylcholine↗
PubMed1995

Amplification of a circular episome carrying an inverted repeat of the DFR1 locus and adjacent autonomously replicating sequence element of Saccharomyces cerevisiae.

Lack of suitable amplification markers has hindered the use of the yeast system for investigating the mechanism of gene amplification in a eukaryote with a simple genome and well defined genetic system. Recently, methotrexate has been used to select for Saccharomyces cerevisiae mutants with de novo amplification of the dihydrofolate reductase gene (DFR1) (Huang, T. (1993) In Vivo Disruption and de Novo Amplification of the DFR1 Gene Encoding Dihydrofolate Reductase in Saccharomyces cerevisiae. Ph. D. thesis, University of Alberta, Edmonton, Canada). We report here the detailed structure of a DFR1 episome amplified in methotrexate-resistant strain 25-1. The extrachromosomal DNA is found predominantly as a single 11-kilobase circular molecule. It consists of a 5.5-kilobase inverted duplication that contains the DFR1 locus and adjacent ARS (autonomously replicating sequence) element. This molecular configuration mimics the inferred structure of double minute chromosomes observed in a number of mammalian amplification systems and suggests that mechanisms that generate amplified DNAs are conserved from yeast to mammals.

Antimycin A↗
PubMed1995

Site and mechanism of antisense inhibition by C-5 propyne oligonucleotides.

Antisense gene inhibition occurs when an oligonucleotide (ON) has sufficient binding affinity such that it hybridizes its reverse complementary target RNA and prevents translation either by causing inactivation of the RNA (possibly by RNase H) or by interfering with a cellular process such as stalling a ribosome. The mechanisms underlying these processes were explored. Cellular antisense inhibition was evaluated in a microinjection assay using ON modifications which precluded or allowed in vitro RNase H cleavage of ON/RNA hybrids. RNase H-independent inhibition of protein synthesis could be achieved by targeting either the 5'-untranslated region or the 5'-splice junction of SV40 large T antigen using 2'-O-allyl phosphodiester ONs which contained C-5 propynylpyrimidines (C-5 propyne). Inhibition at both sites was 20-fold less active than inhibition using RNase H-competent C-5 propyne 2'-deoxy phosphorothioate ONs. In vitro analysis of association and dissociation of the two classes of ONs with complementary RNA showed that the C-5 propyne 2'-O-allyl phosphodiester ON bound to RNA as well as the C-5 propyne 2'-deoxy phosphorothioate ON. In vitro translation assays suggested that the two classes of ONs should yield equivalent antisense effects in the absence of RNase H. Next, ON/T antigen RNA hybrids were injected into the nuclei and cytoplasm of cells. Injection of C-5 propyne 2'-O-allyl phosphodiester ON/RNA hybrids resulted in expression of T antigen, implying that the ONs dissociated from the RNA in cells which likely accounted for their low potency. In contrast, when C-5 propyne 2'-deoxy phosphorothioate ON/T antigen RNA complexes were injected into the nucleus, the duplexes were stable enough to completely block T antigen translation, presumably by RNA inactivation. Thus, a dramatic finding is that C-5 propyne 2'-deoxy phosphorothioate ONs, once hybridized to RNA, are completely effective at preventing mRNA translation. The implication is that further increases in complex stability coupled with effective RNase H cleavage will not result in enhanced potency. We predict that the development of more effective ONs will only come from modifications which increase the rate of ON/RNA complex formation within the nucleus.

Alkynes↗
PubMed1995

Pingyangmycin as a 99mTc carrier in tumor localization.

A simple method of preparation of 99mTc-pingyangmycin (PYM) for clinical use has been established using super-micro-amounts of SnCl2 as a reductant under dark conditions. The labeling efficiency was higher than 96%, and further purification was not necessary. The effect of ascorbic acid on the distribution of 99mTc-PYM had been investigated. Ascorbic acid increased uptake of 99mTc-PYM in the tumor. Tumor uptake increased with increasing concentration of ascorbic acid. Tumor-blood, tumor-liver, tumor-lung ratios at 1.5 h after 99mTc-PYM administration were 5.19 +/- 1.64, 2.71 +/- 0.51 and 4.15 +/- 0.57, respectively. Preliminary clinical trials in nine patients showed that 99mTc-PYM is a potentially useful tracer for tumor detection with good sensitivity and specificity (true positive 7/7, true negative 1/1, and false positive 1/1).

Aged↗
PubMed1995

Controlling cancerous pain with analgesic powder for cancers.

Analgesic powder for cancers, composed of more than 20 Chinese drugs, was applied externally to 91 patients with various kinds of cancers for management of cancerous pain. The results showed that it was remarkably effective in 42 cases, fairly effective in 22, effective in 22, and ineffective in 5, the total effective rate being 94.51%. Animal experiments indicated that the pain threshold was evidently higher in mice treated with this powder on the site of femoral artery of the hind limbs than that of the controls without application of this powder.

Administration, Cutaneous↗
PubMed1995

[Structure and function of FMR].

The widespread basal expression of fragile X gene (FMR1) suggests that it is a house keeping gene, essential to the survival and function of the cells, but unrelated to proliferation and phenogenesis. The spatial temporal specific expression of FMR1 further suggests that it is an important development-regulating gene, essential to development, particularly to the development of CNS and reproductive system, and may play an important role in cell migration and differantiation. It may also be a posttranscription regulator, by binding to mRNA, regulates the posttranscription processing, transportation, translation and localization of mRNAs. The diversity of pathogenesis of Fra(X) individuals may be caused by the variation of the downstream genes regulated by FMR1.

Animals↗
PubMed1995

[Effect of plant polysaccharides on phosphatidylinositol turnover of sarcoma S180 cell membranes].

Mice sarcoma S180 cell membranes, [r-32 P]ATP and plant polysaccharides (PPS, ASPS, TF and lentinan) were incubated together for 5 min at 30 degrees C. Phosphatidylinositides were isolated and subjected to scintillation fluid counting. The results showed that PPS and ASPS, especially the latter, could inhibit the phosphatidylinositol turnover obviously, while TF and lentinan had no such effect.

Animals↗
PubMed1995

[A prospective study on relationship between abnormal nasopharyngeal mucosa and nasopharyngeal carcinoma].

Abnormal nasopharyngeal mucosa was defined as abnormal finding under the examination of nasopharyngoscope. 43541 healthy persons aged 30-64 were observed for 6 years in the high risk area of NPC, by mean of EBV serological and nasopharyngeal cavity examination. The results are as follows. 1. In the high risk area of NPC, abnormal nasopharyngeal mucosa such as follicle hyperplasia and bulge are common in the younger people, especially in the post-roof of the nasopharyngeal cavity. 2. There was no significant difference on statistics between the abnormal and normal groups on the positive rate and GMT of EBV VCA/IgA. Abnormal nasopharyngeal mucosa did not change with the change of VCA/IgA titer. 3. There was significant difference on the prevalence rate of NPC between the abnormal nasopharyngeal mucosa and normal groups except the age, sex factors. There was no confirmation of the abnormal nasopharyngeal mucosa as precancerous lesion.

Adult↗
PubMed1995

[Detection of FMR-1 gene expression by RT-PCR].

Fragile X syndrome [FRA(X)] as the most common form of inherited mental retardation in man has an incidence of one per 1250 and is associated with a fragile site at Xq27.3. A gene was identified at the fragile X locus and was designated Fragile X Mental Retardation-1 (FMR-1). FRA(X) resulted from expansion of (CGG)n trinucleotide repeat in 5' untranslated region of the human FMR-1 gene, and was associated with abnormal methylation of a CpG island 250 bp proximal to this (CGG)n repeat. Males with typical FRA(X) showed repression of FMR-1 transcription and absence of FMR-1 protein, which was believed to contribute to the fragile X phenotype. FMR-1 mRNA extracted from leukocytes in normal and clinically suspected males were detected by RT-PCR. The methylation status and CGG expansion were also studied by PCR and Southern blot. Two of 10 clinically suspected males were found devoid of FMR-1 expression and accompanied with hypermethylation of the CpG island and CGG trinucleotide repeat expansion.

CpG Islands↗