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Biomedical subjects

T T Huang

Publications and source records attributed to T T Huang.

At least 55 records · Page 3Linked to original sources
PubMed1993

Moderate heat treatment increases the penetrability of zonae pellucidae of salt-stored mammalian oocytes by spermatozoa.

The zona pellucida of mammalian oocytes stored in highly concentrated solutions of neutral salts is known to retain its biological and biochemical properties. However, the zona may become resistant to sperm penetration as the storage period is increased. In cattle and hamsters, the penetrability of zonae of salt-stored oocytes was restored or increased by treating the oocytes with moderate heat without altering the gross morphology of the zona. Although this technique did not work for salt-stored human ova, this may have been due to the use of so-called inseminated-unfertilised ova which (1) may have been fertilised but failed to activate, or (2) were not fertilised because of functionally defective zonae.

Animals↗
PubMed1992

Relationship of resistance to oxygen free radicals to CuZn-superoxide dismutase activity in transgenic, transfected, and trisomic cells.

Although CuZn-superoxide dismutase (CuZnSOD) has been shown to reduce oxidative damage in several systems, the quantitative relationship between the degree of protection and CuZnSOD activity has not been well investigated. Therefore, the ability of cells to tolerate superoxide toxicity was assessed as a function of endogenous CuZnSOD activity in several mouse and human cell lines with progressively higher levels of CuZnSOD activity. In five lines of fetal fibroblasts derived from SOD1-transgenic mice, with CuZnSOD activities of 1.7- to 7.1-fold the nontransgenic level and no changes in the cellular glutathione peroxidase (GSHPx) activity, a direct relationship (r = 0.97) between the LD50 to paraquat and enzyme activity was observed, suggesting that CuZnSOD activity is the single most important factor in determining the paraquat LD50. Mouse trisomy 16 fetal fibroblasts and human trisomy 21 lung fibroblasts, both expressing a 1.5-fold increase in CuZnSOD activity, were 1.5-fold more tolerant to paraquat than were their diploid counterparts. Furthermore, the protective effect of CuZnSOD at the DNA level, as shown by reduced thymine glycol generation, was demonstrated in paraquat-treated transgenic fibroblasts. A direct relationship (r = 0.78) of paraquat LD50 and CuZnSOD activity was also observed with a panel of six lines of SOD1- transfected HeLa cells with 1.6- to 7.3-fold the basal CuZnSOD activity. Moreover, there was no correlation between resistance to paraquat toxicity and the cellular GSHPx and/or catalase activity. Taken together, these results demonstrate a consistently protective effect of endogenous CuZnSOD against superoxide toxicity in both primary and transformed cell lines.

Animals↗
PubMed1992

Reconstruction of the lacrimal excretory system.

Primary surgical repair of the lacrimal drainage apparatus may not be feasible in patients with maxillofacial injuries involving extensive structural damage. If secondary restoration of the tear duct is not possible, reconstruction of an aberrant passage then will be necessary for tear drainage. Although the Pyrex conjunctivorhinostomy has been considered to be the most effective modality of treatment in managing patients with tear-duct dysfunction, this procedure can be plagued with problems of tube dislodgment, infection, and cicatricial tract obliteration. The patients are, furthermore, required to wear the device for the remainder of their lives. Autologous material is therefore best suited for reconstructing a conduit. A medially based mucosal flap fashioned in the lower palpebral conjunctiva, 5 mm in anteroposterior dimension and 15 mm in horizontal length, can be used to form a conduit. This is then sutured to a flap mobilized from the nasal cavity, the lacrimal sac, or the maxillary antrum. In the past 15 years, a total of 24 fistulous tracts utilizing this technique were reconstructed in 20 patients with tear-duct obstruction. The experience accumulated from managing this group of patients forms the basis of this report.

Adolescent↗
PubMed1992

The role of superoxide anions in the establishment of an interferon-alpha-mediated antiviral state.

It has been suggested that CuZn-superoxide dismutase (CuZnSOD) is required for the establishment of an interferon (IFN)-mediated antiviral state. To investigate this possibility further, a panel of 6 stably transfected HeLa clones, expressing CuZnSOD activity from 1.6 to 7.3 times the normal level, were treated with different concentrations of recombinant human interferon alpha A (rHuIFN-alpha A) followed by challenge with vesicular stomatitis virus (VSV). A biphasic response curve was generated (r = 0.87, p less than 0.025). Clones with up to 3-fold basal level CuZnSOD activity exhibited an inverse relationship between their ability to generate an IFN-alpha-mediated antiviral state and CuZnSOD activity: the higher the CuZnSOD activity, the lower the sensitivity to IFN-alpha and the more IFN-alpha required for antiviral defense. Clones with between 4 to 7.3 times higher CuZnSOD activity than the non-transfected HeLa control showed a direct relationship between the CuZnSOD activity and the sensitivity to IFN-alpha. Furthermore, in agreement with the results obtained with the SOD1-transfected HeLa cells with up to 3 times the basal SOD activity, fetal fibroblasts derived from SOD1-transgenic mouse strains, TgHS-229 and TgHS-218, which also express 3 times the basal CuZnSOD activity, required higher IFN-alpha to achieve 50% protection. These results suggest a possible role for superoxide anion in the establishment of IFN-mediated antiviral effect, especially in the dose-response region in which the inverse relationship between the generation of the IFN-alpha-mediated antiviral state and CuZnSOD activity was observed. To assess this possibility, allopurinol was used as a xanthine oxidase inhibitor and hydroxyl radical scavenger in the IFN-alpha-mediated antiviral assay. Addition of 3 mM allopurinol diminished the IFN-mediated antiviral effect by between 40 and 50% (p less than 0.01), and there was a reduction in superoxide generation (p less than 0.05). The degree of reduction caused by allopurinol treatment was higher at an IFN-alpha concentration of 10 U/ml than at 100 U/ml, and there was no correlation between CuZnSOD activity and the degree of reduction. To establish further the role of superoxide as an antiviral agent, paraquat was used as a superoxide generator in the absence of IFN-alpha in the antiviral assay. Although paraquat at high concentrations is toxic to the cells, it actually showed a protective effect against VSV infection, and an inverse relationship (r = 0.79, r less than 0.025) between cell survival and CuZnSOD activity was observed with 150 mM paraquat treatment.(ABSTRACT TRUNCATED AT 400 WORDS)

Allopurinol↗
PubMed1992

Mock embryo transfer in early luteal phase, the cycle before in vitro fertilization and embryo transfer: a descriptive study.

OBJECTIVE: To investigate visually the uterine retention or sequestration of boluses of radiopaque dye, mimicking embryo transfer (ET). DESIGN: During the cycle before in vitro fertilization (IVF) and ET, patients underwent a mock ET of 40 microL of radiopaque dye into the uterine cavity. The patient was positioned supine for retroverted or axial and knee chest for anteverted uteri. The position of the dye at injection, during and after catheter removal, and during patient roll over and standing was monitored. SETTING: Treatment of infertility in a private practice. PATIENTS: Thirty-four IVF patients. INTERVENTIONS: During the cycle before IVF/ET, patients underwent a mock ET using a bolus of 40 microL of radiopaque dye. MAIN OUTCOME MEASURES: Planned before visual observation began. RESULTS: The dye remained primarily in the uterine cavity in only 68% (optimum ET position is knee chest for anteverted and supine for retroverted or axial uterus) and 48% (nonoptimum position is supine for anteverted uterus) at mock ET; in those groups, a 33% clinical pregnancy rate (PR) per retrieval resulted. Dye motility into the fallopian tube(s), cervix, and/or vagina is 38.2%, 8.8%, and 11.8%, respectively. CONCLUSIONS: If the mock ET had been the actual ET, 32% (optimum ET position) and 52% (nonoptimum ET position) of all patients would have lost their opportunity for pregnancy as a result of the ET procedure. Our 33% PR per retrieval among those patients who retained the dye in utero is more consistent with our expectations, given the advanced technologies of IVF/ET today.

Embryo Transfer↗
PubMed1991

A mechanism for differential release of acrosomal enzymes during the acrosome reaction.

To study the organization of fertilization enzymes in the sperm acrosome, we isolated and characterized two physicochemically distinct acrosomal fractions of guinea-pig spermatozoa. A soluble fraction contained the 25,000-Mr acrosomal autoantigen, AA1, and most of the acrosomal hyaluronidase and dipeptidyl peptidase II activity. A particulate fraction, designated acrosomal matrix (AM), consisted of membraneless crescent-shaped structures, and contained most of the acrosomal proacrosin. The AM also contained a 28,000-Mr putative proacrosin-binding protein, and a very-high-Mr component which, on reduction, was dissociated into 48,000-Mr and 67,000-Mr subunits. Autoproteolytic dissolution of the AM correlated with proteolysis by acrosin of the 28,000-Mr and 48,000-Mr AM molecules. Components of both the AM and the soluble fraction were localized by immuno-electron microscopy to the electron-dense region of the guinea-pig sperm acrosome. We conclude that acrosomal molecules are segregated into soluble and matrix compartments. This segregation is a function of disulphide bonding and non-covalent interactions among the relatively few components of the AM. Association of acrosin with the AM may be the mechanism by which this enzyme's release from the spermatozoon during the acrosome reaction is delayed relative to the release of other acrosomal molecules.

Acrosin↗
PubMed1990

Comparison of phosphorylation of elongation factor 1 from different species by casein kinase II.

One subunit of EF-1 or EF-1 beta gamma from Artemia salina, wheat germ and rabbit reticulocytes is modified by casein kinase II. The subunit corresponds to the low Mr subunit of EF-1 (26,000-36,000) which functions along with a higher Mr subunit (46,000-48,000), to catalyze the exchange of GDP for GTP on EF-1 alpha. The factor from Artemia and wheat germ is phosphorylated directly on serine by casein kinase II whereas a modulatory compound is required for phosphorylation of EF-1 from reticulocytes. Polylysine increases the rate of phosphorylation of EF-1 from reticulocytes by 24-fold; both serine and threonine are modified. This suggests that polylysine may be substituting for a physiological regulatory compound which modulates phosphorylation in vivo.

Animals↗
PubMed1990

Breast and subscapular pain following submuscular placement of breast prostheses.

The technique of placing the breast prosthesis beneath the pectoralis major and the serratus anterior muscles appears to minimize the incidence of the firm breast following breast reconstruction commonly seen with other techniques. However, in 8 of 146 individuals I have noted a problem with pain in the lateral aspect of the breast mound and the subscapular area, along with a depressed deformity superomedially and an unsightly bulge inferolaterally and/or laterally. Surgical exploration of the breast mound showed no abnormalities within the submuscular compartment. However, in all instances, the serratus anterior muscles were found to be detached from the ribcage all the way to the point beyond the posterior axillary line. While continuous pressure exerted on the serratus muscles by the implant appears to play an important role in the pathogenesis of this clinical entity, the onset of problems was usually delayed. Removal of the implants or repair of the cavity defects is necessary for patients who have developed this problem.

Adult↗
PubMed1989

Longitudinal assessment of breast development in adolescent female patients with burns involving the nipple-areolar complex.

Long-term follow-up of breast development in adolescent female patients with burns of the anterior chest wall is poorly documented. Between 1971 and 1976, 28 female patients with photographic documentation of burns to the anterior chest wall involving the nipple-areolar complex were reviewed. All patients were followed at least until their early teens. The mean age at the time of thermal injury was 5.9 +/- 2.5 years, with a mean follow-up time of 8.9 +/- 2.6 years. Thirteen patients (46 percent) were admitted to the Shriners Burns Institute in Galveston for acute care of their burns. Fifteen patients (54 percent) were referred for long-term follow-up or specific reconstructive procedures following care of the acute burns. In spite of significant thermal injury to the anterior chest wall with involvement of the nipple-areolar complex, no patient failed to develop breasts. Twenty patients (71 percent) required releases of the anterior chest wall to assist breast development. All anterior chest wall releases were accomplished with the use of skin grafts or local skin flaps.

Adolescent↗
PubMed1989

The streptokinase gene of group A streptococci: cloning, expression in Escherichia coli, and sequence analysis.

The gene specifying the group A streptokinase (ska) gene was cloned from an M type 49 strain of Streptococcus pyogenes and shown to express in Escherichia coli. The nucleotide sequence of the DNA fragment carrying ska was determined and compared to that of the group C streptokinase gene (skc). There is 90% sequence identity between the two genes, with highly conserved transcription and translation control regions. The deduced amino acid sequence of the group A streptokinase (SKA) contains the same number of amino acids as that of group C streptokinase, with 85% sequence identity between the two proteins. Among 440 amino acid residues specified by the coding sequence, there are 62 non-identical residues with 45 conserved and 17 non-conserved residues. The non-identical residues are located in two major regions, spanning residues 174 to 244 and 270 to 290, with 40 and 10 amino acid changes, respectively. The sequence differences provide an explanation at the molecular level for the previous findings of immunological and chemical heterogeneity among streptokinase produced by pathogenic streptococci.

Amino Acid Sequence↗
PubMed1989

Heterogeneity of the streptokinase gene in group A streptococci.

A molecular epidemiological study was conducted to determine the distribution of the streptokinase gene in group A streptococcal strains of different M types and in other streptococcal species. Plasmid pNC1, containing only the internal coding sequence of the streptokinase gene from group C streptococcal strain H46A, was used as a DNA probe in colony and Southern hybridization experiments. Only the pathogenic group A, C, and G streptococci contained a streptokinase gene; 12 other Lancefield group strains did not. A total of 134 group A strains, including 61 M types and 6 T types, were tested. Although only 62% (83 of 134) of the strains tested showed positive streptokinase activity by the casein-plasminogen overlay assay, all strains contained the streptokinase gene as evidenced by strong hybridization with the pNC1 probe. Southern blot DNA hybridizations were carried out with 101 strains of group A streptococci. The restriction enzymes HindIII and HaeIII were used to digest the genomic DNA. Six hybridization patterns were observed after HindIII digestion. Double hybridization bands appeared in all of the patterns, which indicated the existence of a highly conserved HindIII site. More complex hybridization results were obtained after HaeIII digestion. Twelve hybridization patterns were observed; three were characterized by a single hybridization band, and nine were characterized by double bands. Variations in hybridization patterns were observed in strains of both the same and different serotypes. The overall results at the gene level indicate that there is considerable heterogeneity among the streptokinases of group A streptococci, consistent with previous findings of immunological and chemical differences among streptokinases of group A streptococci.

DNA Probes↗
PubMed1988

Purification and characterization of the primary acrosomal autoantigen of guinea pig epididymal spermatozoa.

Previous studies showed that sperm auto- and alloantigens participate in guinea pig (GP) fertilization. In an effort to determine how alloantibodies to GP sperm acrosomal contents (AC) inhibit fertilization, we identified acrosomal auto- and alloantigens using Western blots. The predominant autoantigens migrated with Mr = 25,000, Mr = 51,000, and Mr = 55,000 under nonreducing conditions. The primary (Mr = 25,000) acrosomal autoantigen, AA1, was purified to homogeneity from AC by gel filtration, cation-exchange chromatography, chromatofocusing, and a final gel filtration. We also purified AA1 from an acidic glycerol extract of spermatozoa by gel filtration, chromatofocusing, and high-performance liquid chromatography on hydroxylapatite. AA1 is a protein and shares at least one antigenic determinant with a 51,000 Mr acrosomal component. AA1 is acrosome-specific, as determined by immunoabsorption and by indirect immunofluorescence on testicular cells. By quantitative enzyme-linked immunosorbent assay, AA1 comprises 6.4% of acrosomal protein in GP spermatozoa. On the basis of its physiochemical properties and localization, we conclude that AA1 is a unique sperm autoantigen. Surprisingly, several antibody preparations, including allo- and heteroantibodies with high anti-AA1 titers, did not inhibit fertilization in vitro. Thus, the mechanism by which alloantibodies to AC inhibit GP fertilization in vitro is not by binding to AA1.

Acrosome↗
PubMed1988

Treatment of burn alopecia with tissue expanders in children.

During the past 18 months, 60 tissue expanders were utilized in the reconstruction of 42 children with burn alopecia of the scalp not amenable to a single excision and primary closure at the Shriners Burns Institute in Galveston, Texas. The children were grouped according to the degree of alopecia. All patients with defects of 15 percent or less of the total hair-bearing scalp were able to obtain complete closure of their defects with two operations, i.e., one to place the expander and the second to remove the expander and advance the flaps. Some patients with defects up to 40 percent were closed with serial expansion. Patients with even larger defects had a significant reduction in the percentage of alopecia and benefited from re-creation of anterior hairlines. We have encountered a postoperative complication rate of 10 percent. When compared to previous methods of treating burn alopecia, tissue expansion allows a more rapid closure, fewer operations and coincident anesthetics, and decreased total length of hospitalization.

Adolescent↗
PubMed1988

Sequence analysis of the glucosyltransferase A gene (gtfA) from Streptococcus mutans Ingbritt.

The complete nucleotide sequence of a 2.4-kilobase fragment containing the glucosyltransferase A gene (gtfA) of Streptococcus mutans Ingbritt (serotype c) was determined. The gtfA gene contains 481 codons and specifies a protein of molecular weight 55,665. There is no evidence of a signal peptide in the protein or that the glucosyltransferase A enzyme is secreted. No sequence homologies were observed between the gtfA gene or protein and the gtfI or gtfB gene and its protein.

Amino Acid Sequence↗
PubMed1987

Routine use of a suction drain in facial rhytidoplasty.

The effectiveness of a suction drain in facial rhytidoplasty was evaluated in 46 women ranging in age from 41 to 78 years. The drain was placed on the left side of the face in 16 and on the right in 14, and no drain was used in 16 patients. The drain was removed in 24 hours regardless of the amount aspirated, which varied between 0 and 25 ml, with an average of 7.8 ml. Although none of these patients developed a hematoma while the drain was in place, a hematoma did occur in 1 patient on the drain side following its removal. Despite the variable quantities of fluid aspirated, there was no clinical difference in swelling noted around the face and neck area when the two sides were compared. Similarly, one could not distinguish this group of patients from those 16 who did not receive the drain. The routine use of continuous suction drains for patients undergoing rhytidoplasty is therefore probably unnecessary.

Adult↗