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Biomedical subjects

Q Huang

Publications and source records attributed to Q Huang.

322 records · Page 18Linked to original sources
PubMed1985

Studies on beta-lactoglobulin as an experimental allergen in rats.

The allergenicity of bovine beta-lactoglobulin (beta-LG) in rats was investigated by measurement of both mast cell-bound and circulating IgE antibody produced in response to immunisation with this cow's milk constituent. The responsiveness of the animals' peritoneal mast cells to in vitro challenge with beta-LG was determined by measurement of release of radiolabelled 5-hydroxytryptamine. Using aluminium hydroxide gel as adjuvant, the responsiveness of mast cells to beta-LG was transient, peaking at 21 days after immunisation. The optimal dose of injected beta-LG was 100 micrograms. Circulating IgE antibody to beta-LG, measured by ELISA, was also detected transiently during the 3rd week post-immunisation.

Adjuvants, Immunologic↗
PubMed1985

Investigation of the allergenicity of beta-lactoglobulin and its cleavage fragments.

Fragments of beta-lactoglobulin were produced by proteolytic cleavage with trypsin, and chemical cleavage with cyanogen bromide, followed by gel filtration on Sephadex G-50. The antigenicity and allergenicity of the products were studied, before and after reductive cleavage by treatment with 2-mercaptoethanol. The former was determined by inhibition ELISA using IgG anti-beta-lactoglobulin raised in rabbits, whilst the latter was determined by inhibition ELISA and mast cell challenge, using respectively the sera and peritoneal cells of rats experimentally sensitised to beta-lactoglobulin. The findings raise interesting points about the structural basis of allergenicity in relation to antigenicity.

Allergens↗
PubMedDate not supplied

Phrenic response to hypercapnia in the unanesthetized, decerbrate, newborn rat.

We developed a decerebrate, vagotomized, newborn rat preparation to investigate brainstem respiratory control mechanisms without the influence of anesthesia, supra-pontine structures, or vagally mediated feedback mechanisms. We measured the changes in phrenic nerve electrical activity in response to breathing 3% and 5% CO2 in unanesthetized, vagotomized, decerebrate newborn rats from 0 to 10 days of age and compared them with the changes in anesthetized, vagotomized, newborn rats and adult, vagotomized, decerebrate or anesthetized, animals. Phrenic nerve activity was irregular in the young newborn rats and became more regular between 7 and 10 days of age. T1 and T1/Ttot increased with age but increasing age had no influence on the response to CO2. The response to CO2 was dominated by increases in phrenic amplitude, minute activity, and inspiratory slope with no change in timing variables. These responses are similar to those that have been reported previously in vagally intact animals, suggesting that vagal feedback contributes little to the response to hypercapnia in the newborn rat. In summary, decerebrate newborn rats consistently respond to hypercapnia by increasing inspiratory drive similar to conscious animals.

Animals↗
PubMedDate not supplied

The mast cell response to substance P: effects of neuraminidase, limulin, and some novel synthetic peptide antagonists.

We have investigated certain aspects of the mechanism whereby substance P triggers secretion of 5-hydroxytryptamine (5-HT) from rat peritoneal mast cells in vitro. Substance P-induced release of 5-HT was inhibited following pretreatment of rat peritoneal cells with 0.01-1.0 units/ml neuraminidase; secretion induced by anti-IgE antibody was inhibited by pretreatment with 1.0 units/ml but not by lower concentrations of enzyme. Addition of the sialic acid-rich substances N-acetyl-neuraminlactose (up to 1.0 mM) and mucin (up to 1.0 mg/ml) to substance P in free solution failed to block the activity of the neuropeptide. Limulin, a sialic acid-specific lectin, failed to block substance P-induced secretion of 5-HT, but was found to possess intrinsic non-lytic secretory activity (at 5-20 micrograms/ml). Release of 5-HT induced by limulin was independent of that induced by substance P. A range of octapeptides incorporating the C-terminal sequence Gly-Ser-Phe-Phe, but differing in degree of cationicity and positioning of cationic residues in the four N-terminal positions, were tested for their capacity to antagonise the mast cell-triggering activity of substance P. A peptide incorporating two lysine residues at the N-terminus was found to have partial substance P antagonist activity; no effects on IgE-mediated secretion were observed.

Animals↗
PubMedDate not supplied

(Aminomethyl)phosphonate derivatives of oligonucleotides.

Oligothymidylate (aminomethyl)phosphonates have been prepared, and their enzymatic and physicochemical properties have been studied. The individual isomers of the protected dimers have been separated, characterized, and incorporated into oligonucleotides in which the backbone consists of alternating (aminomethyl)phosphonate and phosphodiester linkages. One of these net neutral, single isomer oligonucleotides forms a duplex with its complementary sequence which is more stable than the corresponding natural counterpart, whereas the other isomer is considerably less stable. Specificity of hybridization is maintained, as determined by the reduction in melting temperature observed upon the introduction of mismatches into the complementary strand of the duplex. The (aminomethyl)-phosphonate linkage is stable toward enzymatic degradation but can be hydrolyzed in aqueous solution at elevated temperature.

Base Sequence↗
PubMedDate not supplied

A simple method for fixation and microdissection of frozen fresh tissue sections for molecular cytogenetic analysis of cancers.

Microdissection has been widely used for procuring DNA from specific microscopic regions of formalin fixed, paraffin embedded tissue sections. We have developed a method for fixation and microdissection of frozen fresh biopsy tissue sections. Five micrometer frozen fresh tissue sections were fixed with ethanol and stored at room temperature. Well defined regions from hematoxylin and eosin (H & E) stained or unstained sections were briefly steamed and microdissected using a needle. The dissected tissue was digested with proteinase K and DNA was isolated. Whole genome amplifications were obtained by degenerate oligonucleotide primed polymerase chain reaction (DOP-PCR) from these samples. The reliability of this technique was demonstrated by comparing conventional comparative genomic hybridization (CGH) with DOP-PCR-CGH. The advantages of this method are that frozen fresh sections can be fixed easily and stored for more than 4 years, it is easy to microdissect and pick-up very minute regions (0.1 mm(2)), and it is rapid; microdissection and purification can be accomplished within 3 h. Using DNA from microdissected sections, DOP-PCR-CGH revealed genetic abnormalities more accurately than conventional CGH. Although this novel method was demonstrated using DOP-PCR-CGH, we believe that it will be useful for other genetic analyses of specific small regions and cell populations. We also observed whether storage time, H & E staining and crude DNA extracts affected the quality of amplified DNA. DNA integrity was maintained for at least 49 months in ethanol fixed sections that were stored at room temperature, but DNA was gradually degraded after one month if the ethanol fixed sections had been H & E stained and stored. When crude DNA extracts from H & E stained sections were used, the size of the DOP-PCR product was reduced. Our study suggests that ethanol fixed tissue sections may be stored at room temperature for at least 4 years without DNA degradation, the H & E stains may not affect the quality of amplified DNA, but H & E or other components in the staining process may reduce the size of DOP-PCR product, which is critical for the quality of CGH hybridization.

Biopsy↗