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Biomedical subjects

D Huynh

Publications and source records attributed to D Huynh.

11 recordsLinked to original sources
PubMed2002

Immobilized halogenophenylcarbamate derivatives of cellulose as novel stationary phases for enantioselective drug analysis.

Three different halogeno-phenylcarbamate derivatives of cellulose have been prepared and coated on silica gel. The coated materials have been immobilized and their chiral recognition ability as chiral stationary phase (CSP) has been evaluated with a set of reference racemates, including several drugs such as lormetazepam, glutethimide, and warfarin, using various mobile phase mixtures. The novel phases were found to exhibit unique enantioselective properties compared with more established polysaccharide-based CSPs. A good resolution of all racemates could be successfully achieved on at least one of the immobilized CSPs. Moreover, it has been pointed out that selectivity may considerably vary with the composition of the mobile phase.

Carbamates↗
PubMed1999

Fine specificity and MHC restriction of trinitrophenyl-specific CTL.

In this study, the fine specificity and MHC restriction of a CTL response specific to the trinitrophenyl (TNP) hapten was analyzed. Based on the structure of peptide/Kb complexes and ternary TCR/Ag/MHC complexes, four TNP peptides, two octamers, and two nonamers were chosen for eliciting anti-TNP CTL responses. Hapten was conjugated at position 4 in the octamers and at position 5 in the nonamers, positions which should allow engagement of the hapten by TCRs. Potent CTL activity for each of the TNP peptides was obtained that was highly hapten-specific; however, there were considerable differences in the extent of cross-reactivity with other TNP peptides, with the octamers generating more cross-reactive CTL than the nonamers. MHC restriction analysis suggested that anti-hapten responses were less dependent on MHC recognition than anti-peptide responses. This was evidenced by the relative ease of detecting cross-reactivity to haptenated peptides presented by allo-MHC and by the relative insensitivity of anti-hapten vs anti-peptide CTL to mutations in the Kb molecule at potential TCR interaction sites. One potential explanation for this insensitivity to MHC mutation was the finding that the anti-hapten response appeared to be of higher avidity, since a > 100-fold difference in the amount of Ag required to sensitize target cells was found between these two types of Ags.

Animals↗
PubMed1998

Initiating genetic events in small renal neoplasms detected by comparative genomic hybridization.

PURPOSE: To identify the genetic alterations associated with renal adenomas. MATERIALS AND METHODS: We analyzed 37 renal adenomas obtained at autopsy (23 papillary and 14 non-papillary) by comparative genomic hybridization. RESULTS: In papillary tumors, the median number of gains and losses of genetic material per tumor was 2.0 and 1.0, respectively. Papillary tumors were characterized predominantly by gains of genetic material on chromosomes 7 (57%), 17 (35%), 16 (26%), 12 (26%), 3 (22%), 20 (22%) and loss of a sex chromosome (83%). In 6 papillary tumors less than or equal to 5 mm. in diameter, gain of chromosome 7 occurred in 4 specimens. Initiating events for papillary renal adenomas include gain of chromosome 7 and loss of a sex chromosome. In non-papillary tumors, the median number of gains and losses of genetic material per tumor was 1.0 and 1.0, respectively. Non-papillary tumors were characterized by loss of genetic material on chromosome 3p (50%), loss of a sex chromosome (36%) and a gain of chromosome 5 (43%). The initiating event for non-papillary renal adenomas is the loss of chromosome 3p. CONCLUSIONS: Renal adenomas demonstrate similar genetic alterations as clinically detected renal cell carcinomas. Their clinically indolent course may, in part, be a result of the lower number of genetic alterations per tumor than their clinically detected counterparts. Renal adenomas are thus small carcinomas which have not yet acquired the necessary genetic alterations leading to tumor progression.

Aged↗
PubMed1996

Comparative genomic hybridization for genetic analysis of renal oncocytomas.

Renal oncocytomas are uncommon tumors of the kidney that are considered to be of low malignant potential. Neither conventional cytogenetic nor restriction fragment length polymorphism analyses have identified consistent genetic alterations in their genomic DNA. The purpose of the present study was to identify the genetic alterations associated with the development of renal oncocytomas. We studied 13 renal oncocytomas by using comparative genomic hybridization, and we identified loss of genetic material from chromosomes 1 and/or 14 in six of these tumors. These alterations may represent early genetic events in the development of these tumors.

Adenoma, Oxyphilic↗
PubMed1994

[For practical salivary flowmetry. A weighing technic].

No one method of salivary flowmetry has been found to be practical, reliable and fully significant. Consequently, the diagnosis of salivary gland failure remains uncertain and imprecise even though the diagnostic question is often raised. A simplified and effective weight measurement could be more widely used. Saliva is sampled easily with small compresses inserted into the sublingual groove and left in potion for 5 minutes without deglutition or mastication for a saliva collection and close as possible to the baseline level; then for 1 minute after mastication to collect stimulated secretion. The compresses are then weighted. The reliability of this method must be confirmed with a multicentric study.

Absorption↗
PubMed1992

Leuprolide acetate elevates prolactin during ovarian stimulation with gonadotropins.

OBJECTIVE: The purpose of this study was to determine whether gonadotropin-releasing hormone agonist further increases the prolactin rise accompanying ovarian stimulation. DESIGN: Serum prolactin concentrations were compared between cycles with and cycles without the use of leuprolide acetate (LA) matched for estradiol levels. Relationships of prolactin levels to cycle outcomes were examined. SETTING: The study took place at a private fertility center. PATIENTS: Patients were women receiving stimulation for oocyte retrieval using human menopausal gonadotropins. INTERVENTIONS: No interventions were used. MAIN OUTCOME MEASURES: Serum prolactin level, fertilization rate, embryo quality, and pregnancy were the main outcome measures. RESULTS: Higher serum prolactin was associated with both higher estradiol levels and use of LA but did not have any effects on fertilization rate, embryo quality, or occurrence of pregnancy. CONCLUSION: LA stimulates prolactin release during ovarian stimulation but without apparent consequence.

Chorionic Gonadotropin↗
PubMed1991

Lower pregnancy rate with premature luteinization during pituitary suppression with leuprolide acetate.

The relationship of the circulating level of progesterone (P) on the day of human chorionic gonadotropin (hCG) injection to occurrence of clinical pregnancy was examined in 133 leuprolide acetate human menopausal gonadotropin (hMG) in vitro fertilization cycles in women having at least three embryos transferred. Progesterone concentrations greater than 0.5 ng/mL were associated with a significantly lower rate of pregnancy (12/59, 20%) compared with less than 0.5 ng/mL (40/74, 54%, P less than 0.005). The higher P cycles were associated with greater patient age and hMG dose, although these relationships appeared to be indirect. Luteinizing hormone (LH) concentrations remained suppressed. Ovarian stimulation may cause excessive luteinization and an adverse cycle outcome even in the presence of low LH levels. Prospective use of P levels may be helpful to determine optimal hCG timing.

Adult↗
PubMed1989

Routine pituitary suppression with leuprolide before ovarian stimulation for oocyte retrieval.

Pituitary suppression with leuprolide acetate (LA) was used before and during ovarian stimulation with human menopausal gonadotropins in 45 consecutive women having their first cycle of in vitro fertilization embryo transfer (IVF-ET). As anticipated, a low rate of cycle cancellation (6.7%) was necessary for poor responses. Follicles were allowed to develop to a larger diameter than with our prior protocol without LA. On the day of human chorionic gonadotropin (hCG), 11.5 + 0.7 follicles of at least 1.0 cm were visualized; 11.7 + 0.9 oocytes were retrieved; 67.5% fertilized and 6.7 + 0.6 normal embryos were available for transfer. Of the 3.4 + 0.1 embryos transferred per patient, 24.6% implanted. The rates of clinical pregnancy per retrieval and per stimulation were 54% and 47%, respectively, of which 23.8% aborted. Routine use of LA resulted in a highly efficient level of ongoing pregnancy per initiated cycle, and therefore may produce a superior first cycle for IVF-ET.

Adult↗
PubMed1988

Timing of initiation and dose schedule of leuprolide influence the time course of ovarian suppression.

The time course of suppression of ovarian estrogen production and follicular development with leuprolide was examined in 40 normal women before ovarian stimulation for in vitro fertilization (IVF). Initiation of leuprolide during the midluteal phase caused a significantly more prompt suppression than when treatment was started during the early follicular phase (day 1). Injection of the same total amount of leuprolide in two divided doses also caused a significantly more prompt suppression. These two methods were consistent enough to make routine use of leuprolide practical before ovarian stimulation for IVF.

Estradiol↗
PubMed1985

[Oral and cutaneous lesions in Crohn's disease. A case report].

Cutaneous and buccal manifestations of Crohn's disease are common. They are diagnostically helpful either by their specificity or from a biopsy which whilst access is easy offers less satisfactory results with buccal lesions. Stomatological clinical aspects are varied, most commonly of aphthoid or vesicular stomatitis type (as in the case reported here).

Adult↗