Search PubMed⌕ Search

Biomedical subjects

J C Huang

Publications and source records attributed to J C Huang.

At least 55 records · Page 3Linked to original sources

Differential expression of photoreceptor-specific proteins during disease and degeneration in the progressive rod-cone degeneration (prcd) retina.

Progressive rod-cone degeneration (prcd) is a late-onset hereditary retinal degeneration characterized by normal development of photoreceptors prior to degeneration and death of visual cells. We reported previously that expression of opsin mRNA and protein decreases prior to visual cell degeneration. To examine the specificity of this reduction, we have used immunocytochemistry to correlate photoreceptor-specific protein expression with visual cell disease progression. Eyes from light-adapted age-matched control and prcd-affected dogs were fixed in paraformaldehyde, embedded in diethylene glycol distearate (DGD) wax, and reacted with antibodies specific to interphotoreceptor retinoid-binding protein (IRBP), S-antigen, opsin, phosducin, gamma-phosphodiesterase (gamma-PDE), and beta 1-transducin. While IRBP expression did not change with disease progression, immunoreactivity to other proteins varied. For S-antigen and opsin, immunoreactivity decreased dramatically with the transition from photoreceptor disease to degeneration; gamma-PDE immunolabeling in rods also decreased, but the reduction was less abrupt. However, for two other proteins (phosducin and beta 1-transducin), immunoreactivity increased initially and was redistributed (particularly to the rod outer segment) in early disease (stage 1). Our results show that there is a differential expression of photoreceptor-specific proteins with disease and degeneration that is not uniform for all the gene products examined; expression can be decreased, altered in distribution or remain unchanged. It is clear that the decrease of opsin expression described previously is not an isolated phenomenon in the progression of prcd, but is part of a more generalized degenerative process which eventually culminates in cell death.

Animals↗

Characterization of a lily tapetal transcript that shares sequence similarity with a class of intracellular pathogenesis-related (IPR) proteins.

This study addresses isolating and characterizing a cDNA clone corresponding to a tapetum-specific transcript, designated as PR-10a from Lilium longiflorum. Anther ontogeny is histologically divided into three consecutive phases. The first encompasses early proliferative stages and differentiation of the locules. The second concerns microspore development from the onset of meiosis through microspore maturation. The final phase involves pollen maturation, originating with microspore mitosis through pollen formation. The lily PR-10a transcript is anther-specific and temporally expressed only at the phase of microspore development during which the tapetal cells become polarized, highly secretory, and exhibit loss of cell walls. The maximal level of PR-10a transcript coincides strictly with the peak of tapetal secretory function. Comparing mRNA and cDNA insert sizes reveals that PR-10a is close to full-length. Sequence analysis demonstrates similarity between the predicted lily PR-10a and asparagus AoPR1 protein, potato pSTH2 and pSTH21 proteins, parsley PcPR1 and PcPR3 proteins, bean PvPR1 and PvPR2 proteins, lupin L1R18B protein, pea 149 protein and a family of major allergens including Cor a 1 of hazel, Car b 1 of hornbeam, Aln g 1 of alder, Bet v 1 of birch and Api g 1 of celery. To the authors' knowledge, this is the first reported organ/tissue-specific IPR protein.

Amino Acid Sequence↗

Preservation of pudendal afferents in sacral rhizotomies.

OBJECTIVE: To assess the effectiveness of pudendal afferent mapping as a tool to minimize the risk of postoperative bowel, bladder, and sexual dysfunction in patients undergoing selective posterior rhizotomies in whom the S2 roots are candidates for rhizotomy. METHODS: One-hundred fourteen children with the diagnosis of cerebral palsy and debilitating spasticity were selected to undergo selective posterior rhizotomies at New York University Medical Center during 1991 through 1995. There were 72 male and 42 female patients with a mean age of 3.8 years. At the time of surgery, none of the patients had clinically relevant bladder dysfunction. Dorsal root action potentials were recorded intraoperatively to map the distribution of pudendal afferent fibers in S1-S3 roots bilaterally before performing the rhizotomies. RESULTS: Pudendal afferent mapping was successful in 105 of 114 patients. In the majority of these patients (56%), the distribution was asymmetrical. S1 roots contributed 4%, S2 roots 60.5%, and S3 roots 35.5% of the overall pudendal afferent activity. The pudendal afferent distribution was often confined to a single level in 18% of the patients or even to a single root in 7.6%. Fifty-six percent of the pathologically responding S2 roots during rhizotomy testing were preserved because of the significant afferent activity, as demonstrated during pudendal mapping. None of the 105 patients so mapped developed long-term bowel or bladder complications. CONCLUSIONS: Pudendal afferent mapping identifies S2 roots that carry a significant number of fibers involved with genital sensation. The preservation of such roots during surgical procedures may be important for sexual function and may also contribute to decreasing postoperative bladder and bowel disturbances.

Action Potentials↗

Standardization and a multilaboratory comparison of Neisseria meningitidis serogroup A and C serum bactericidal assays. The Multilaboratory Study Group.

A standardized serum bactericidal assay (SBA) is required to evaluate the functional activity of antibody produced in response to Neisseria meningitidis serogroup A and C vaccines. We evaluated assay parameters (assay buffer, target strains, growth of target cells, target cell number, complement source and concentration, and methods for growth of surviving bacteria) which may affect the reproducibility of SBA titers. The various assay parameters and specificity of anticapsular antibody to five serogroup A strains (A1, ATCC 13077, F8238, F9205, and F7485) and four serogroup C strains (C11, G7880, G8050, and 1002-90) were evaluated with Centers for Disease Control and Prevention meningococcal quality control sera. The critical assay parameters for the reproducible measurement of SBA titers were found to include the target strain, assay incubation time, and complement. The resulting standardized SBA was used by 10 laboratories to measure functional anticapsular antibody against serogroup A strains F8238 and serogroup C strain C11. In the multilaboratory study, SBA titers were measured in duplicate for 14 pairs of sera (seven adults and seven children) before and after immunization with a quadrivalent polysaccharide (A, C, Y, and W-135) vaccine. The standardized SBA was reliable in all laboratories regardless of experience in performing SBAs. For most sera, intralaboratory reproducibility was +/- 1 dilution; interlaboratory reproducibility was +/- 2 dilutions. The correlation between median titers (interlaboratory) and enzyme-linked immunosorbent assay total antibody concentrations was high for both serogroup A (r = 0.86; P < 0.001; slope = 0.5) and serogroup C (n = 0.86; P < 0.001; slope = 0.7). The specified assay, which includes the critical parameters of target strain, incubation time, and complement source, will facilitate interlaboratory comparisons of the functional antibody produced in response to current or developing serogroup A and C meningococcal vaccines.

Adult↗

Structure-activity relationships of 4-hydroxy-3-nitroquinolin-2(1H)-ones as novel antagonists at the glycine site of N-methyl-D-aspartate receptors.

A series of 4-hydroxy-3-nitroquinolin-2(1H)-ones (HNQs) was synthesized by nitration of the corresponding 2,4-quinolinediols. The HNQs were evaluated as antagonists at the glycine site of NMDA receptors by inhibition of [3H]DCKA binding to rat brain membranes. Selected HNQs were also tested for functional antagonism by electrophysiological assays in Xenopus oocytes expressing either 1a/2C subunits of NMDA receptors or rat brain AMPA receptors. The structure-activity relationships (SAR) of HNQs showed that substitutions in the 5-, 6-, and 7-positions in general increase potency while substitutions in the 8-position cause a sharp reduction in potency. Among the HNQs tested, 5,6,7-trichloro HNQ (8i) was the most potent antagonist with an IC50 of 220 nM in [3H]DCKA binding assay and a Kb of 79 nM from electrophysiological assays. Measured under steady-state conditions HNQ 8i is 240-fold selective for NMDA over AMPA receptors. The SAR of HNQs was compared with those of 1,4-dihydroquinoxaline-2,3-diones (QXs) and 1,2,3,4-tetrahydroquinoline-2,3,4-trione 3-oximes (QTOs). In general, HNQs have similar potencies to QXs with the same benzene ring substitution pattern but are about 10 times less active than the corresponding QTOs. HNQs are more selective for NMDA receptors than the corresponding QXs and QTOs. The similarity of the SAR of HNQs, QXs, and QTOs suggested that these three classes of antagonists might bind to the glycine site in a similar manner. With appropriate substitutions, HNQs represent a new class of potent and highly selective NMDA receptor glycine site antagonists.

Animals↗

Synthesis and structure-activity relationships of 1,2,3,4-tetrahydroquinoline-2,3,4-trione 3-oximes: novel and highly potent antagonists for NMDA receptor glycine site.

A series of 1,2,3,4-tetrahydroquinoline-2,3,4-trione 3-oximes (QTOs) was synthesized and evaluated for antagonism of NMDA receptor glycine site. Glycine site affinity was determined using a [3H]DCKA binding assay in rat brain membranes and electrophysiologically in Xenopus oocytes expressing 1a/2C subunits of cloned rat NMDA receptors. Selected compounds were also assayed for antagonism of AMPA receptors in Xenopus oocytes expressing rat brain poly-(A)+RNA. QTOs were prepared by nitrosation of 2,4-quinolinediols. Structure-activity studies indicated that substitutions in the 5-, 6-, and 7-positions increase potency, whereas substitution in the 8-position causes a decrease in potency. Among the derivatives evaluated, 5,6,7-trichloro-QTO was the most potent antagonist with an IC50 of 7 nM in the [3H]DCKA binding assay and a Kb of 1-2 nM for NMDA receptors expressed in Xenopus oocytes. 5,6,7-Trichloro-QTO also had a Kb of 180 nM for AMPA receptors in electrophysiological assays. The SAR of QTOs was compared with the SAR of 1,4-dihydroquinoxaline-2,3-diones (QXs). For compounds with the same benzene ring substitution pattern, QTOs were generally 5-10 times more potent than the corresponding QXs. QTOs represent a new class of inhibitors of the NMDA receptor which, when appropriately substituted, are among the most potent glycine site antagonists known.

Animals↗

Selective absence of cone outer segment beta 3-transducin immunoreactivity in hereditary cone degeneration (cd).

We have used immunocytochemistry and in situ hybridization to examine the expression of photoreceptor specific genes in retinas of normal dogs and those affected with hereditary cone degeneration (cd), a rare autosomal recessive disorder that selectively affects cones. In the cd retina, cone disease begins early in life; cones are lost by extrusion of the nucleus into the inner segment, and later by displacement of the nucleus, surrounded by a thin rim of cytoplasm, into the interphotoreceptor space. Two micrometer sections from the superior and inferior retinal meridians, extending from the optic disk to the ora serrata, were used for in situ hybridization with a bovine rod opsin and human red/green cone opsin cRNA probes, or were reacted with antibodies directed against photoreceptor-specific proteins and visualized with appropriate biotinylated antibodies. Antibodies against the following proteins were used: alpha- and beta 3-transducins, phosducin, alpha/beta- and gamma-phosphodiesterases, COS-1, and OS-2, opsin, S-antigen and IRBP. Immunoreactivity or hybridization labeling was evaluated in unstained sections; cone pathology was judged in adjacent Toluidine Blue-stained sections. With these methods it was possible to evaluate immunoreactivity or hybridization labeling and cone pathology at the single cell level. Both middle-(COS-1) and short-(OS-2) wavelength-sensitive cones were present in controls and cd affected retinae at 2.2 months, and distinct transcripts of the red/green cone pigment gene were identified in the majority of cones in both normal and affected retinas at this age. However, beta 3-transducin immunoreactivity was completely absent from cd-affected cone outer segments. Both cone types were present but in reduced numbers in older animals (11.5 and 17 months), and no reactivity to beta 3-transducin was noted. No differences were found with the other antibodies used. The specific absence of beta 3-transducin immunoreactivity from the cone outer segments suggests a potential involvement of the beta 3-transducin gene or gene product in the disease process.

Animals↗

The effect of elevated serum progesterone during ovulation induction in in vitro fertilization-embryo transfer.

OBJECTIVE: Our purpose was to determine whether elevated progesterone (P) during ovulation induction in IVF-ET cycles is a poor prognostic factor for achieving pregnancy. DESIGN: We retrospectively reviewed 672 consecutive IVF-ET cycles in which ovulation was performed using luteal LA downregulation and hMG. SETTING: The ART program at the Brigham & Women's Hospital, a tertiary care institution, was the study setting. MAIN OUTCOME MEASURES: Patients were divided into groups by serum P levels at baseline, on stimulation day 5, on the day of hCG injection, and, on the day after hCG injection and the following parameters were compared: duration of luteal LA treatment, number of ampoules of hMG used, estradiol (E2) levels, number of follicles > or = 12 mm, number of follicles > or = 15 mm, number of oocytes, number of normal embryos, number of polyspermic embryos, fertilization rate, implantation rate, and clinical and ongoing/live birth pregnancy rates. RESULTS: Based on serum P level, patients were divided into three groups: Group I, < or = 0.31 ng/ml (conversion factor to SIU, 3.180); Group II, and > 0.3 and < 1.0 ng/ml and Group III, > or = 1.0 ng/ml. Measureable P at baseline was associated with a higher cancellation rate, but no difference in other cycle outcome parameters. Progesterone > 0.31 ng/ml on stimulation day 5 was associated with a higher fertilization rate in Groups II and III, but there was no difference in the clinical pregnancy or ongoing/live birth rates among the three groups. Based on P on the day of hCG administration, Groups II and III had significantly more oocytes and higher fertilization rates than did Group I, however, clinical pregnancy and ongoing/live birth rates were not significantly different. On the day after hCG, there was a trend toward a higher clinical pregnancy rate in Group III, which had younger patients, better follicular recruitment, and more embryos than Groups I or II, but these differences did not reach statistical significance. CONCLUSIONS: Serum P > 0.31 ng/ml during ovulation induction reflects good follicular recruitment, and is not a predictor of IVF outcome.

Adult↗

Epidermal growth factor and basic fibroblast growth factor in peritoneal fluid of women with endometriosis.

OBJECTIVE: To determine and compare the concentrations of epidermal growth factor (EGF) and basic fibroblast growth factor (FGF) in the peritoneal fluid of women with and without endometriosis. DESIGN: Prospective study. SETTING: Tertiary care center affiliated with university medical school. PATIENTS: Forty-two women with endometriosis and 34 women without endometriosis confirmed by laparoscopy. MAIN OUTCOME MEASURES: Epidermal growth factor and basic FGF concentrations were determined by highly sensitive enzyme immunoassays using monoclonal antibodies. RESULT: Approximately 50% of the PF samples had EGF concentrations of > 0.4 pg/mL (conversion factor to SI unit, 0.17) and 90% had basic FGF concentrations of > 1 pg/mL (conversion factor to SI unit, 0.058). Concentrations of EGF or basic FGF in PF did not differ significantly between the two groups. In normal women, there was a significant correlation between EGF and basic FGF during the luteal phase. In women with endometriosis, EGF levels were higher during the luteal phase, but there was no correlation of either EGF or basic FGF levels with the severity of endometriosis. CONCLUSIONS: The concentrations of EGF and basic FGF were highly variable in the PF of women with or without endometriosis and did not differ significantly. The concentrations were so low that neither EGF nor basic FGF in PF could bind to its receptor.

Adult↗

Another look at chronic appendicitis resembling Crohn's disease.

There is an uncommon, enigmatic chronic appendicitis that shares histologic features with typical Crohn's disease (CD), but it presents as appendiceal disease. Although most reported patients remain disease free after appendectomy, a small group progresses to more generalized CD. The density of granulomas is said to separate those patients whose disease remains confined to the appendix from those patients in whom CD develops elsewhere. We reviewed 20 cases of appendicitis morphologically resembling CD and compared them with 16 transmurally inflamed appendices from patients with known CD to evaluate whether any histologic features differentiate between patients in whom recurrent CD will develop in the gut and those in whom it will not. Eleven patients with the primary disease had no granulomas. The remaining nine patients had granulomas, ranging from 0.2 to 28 per cross section. Appendices from patients known to have CD never had more than 10.5 granulomas per cross section. Follow-up in 15 patients with the primary appendiceal disease was from 5 weeks to 11.5 years (median, 30 mo). Thirteen patients remained disease free, but in two, CD developed elsewhere in the gut. One of these had no granulomas, whereas the other one had 21 per cross section. Therefore, according to the data from our study and from other studies, most cases of this Crohn's-like disease of the appendix are self-limited, but a few are not. Histologic features alone, including granuloma density, do not always predict the clinical outcome. Follow-up is necessary.

Adolescent↗

Synthesis and structure-activity relationships of substituted 1,4-dihydroquinoxaline-2,3-diones: antagonists of N-methyl-D-aspartate (NMDA) receptor glycine sites and non-NMDA glutamate receptors.

A series of mono-, di-, tri-, and tetrasubstituted 1,4-dihydroquinoxaline-2,3-diones (QXs) were synthesized and evaluated as antagonists at N-methyl-D-aspartate (NMDA)/glycine sites and alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid-preferring non-NMDA receptors. Antagonist potencies were measured by electrical assays in Xenopus oocytes expressing rat whole brain poly(A)+ RNA. Trisubstituted QXs 17a (ACEA 1021), 17b (ACEA 1031), 24a, and 27, containing a nitro group in the 5 position and halogen in the 6 and 7 positions, displayed high potency (Kb approximately 6-8 nM) at the glycine site, moderate potency at non-NMDA receptors (Kb = 0.9-1.5 microM), and the highest (120-250-fold) selectivity in favor of glycine site antagonism over non-NMDA receptors. Tetrasubstituted QXs 17d,e were more than 100-fold weaker glycine site antagonists than the corresponding trisubstituted QXs with F being better tolerated than Cl as a substituent at the 8 position. Di- and monosubstituted QXs showed progressively weaker antagonism compared to trisubstituted analogues. For example, removal of the 5-nitro group of 17a results in a approximately 100-fold decrease in potency (10a,b,z), while removal of both halogens from 17a results in a approximately 3000-fold decrease in potency (10v). In terms of steady-state inhibition, most QX substitution patterns favor antagonism at NMDA/glycine sites over antagonism at non-NMDA receptors. Among the QXs tested, only 17i was slightly selective for non-NMDA receptors.

Animals↗

Characterization of protein production by caprine placental membranes: identification and immunolocalization of retinol-binding protein.

Caprine chorion, allantois and amnion from days 23, 28, 35, 39 and 45, and yolk sac from day 23 of pregnancy were isolated by dissection and cultured for 24 h in modified minimum essential medium in the presence of [35S] methionine. De novo-synthesized proteins released into the culture medium were analyzed by two-dimensional PAGE and fluorography. Patterns of protein production by these isolated extraembryonic membranes remained relatively unchanged from days 23 to 45 of pregnancy. Electrophoretic profiles of proteins synthesized by allantois and amnion were identical but distinct from that produced by chorion. Yolk sac was the major source of serum-like proteins. An acidic (pI 5.3-6.3) 22 kDa protein, which consisted of four isoelectric variants, was produced by all extraembryonic membranes and demonstrated to immunoreact with antiserum produced against bovine placental retinol-binding protein (RBP). Limited N-terminal sequence analysis of one major isoform indicated that the protein had complete homology with bovine RBP over the first 15 amino acids. Immunoreactive RBP was localized in epithelial cells lining the chorion, allantois and amnion. In this study, we have characterized and compared protein production by isolated extraembryonic membranes through days 23 to 45 of pregnancy and identified the 22 kDa protein as caprine RBP of placental origin.

Amino Acid Sequence↗

Baboon corpus luteum: epidermal growth factor receptor messenger ribonucleic acid expression during early, midluteal, and late luteal phases.

OBJECTIVE: To determine the presence and compare the relative abundance of messenger RNA for epidermal growth factor receptor (EGFR) in baboon corpora lutea of different luteal ages. DESIGN: Prospective controlled nonhuman primate study. SETTING: Animal facility in an academic research institution. PARTICIPANTS: Six adult female baboons with well-defined regular menstrual cycles. Stage of the menstrual cycle was determined by observation and scoring of perineal turgescence. The day of maximal turgescence was referred to as the day of LH surge. INTERVENTION: Ten corpora lutea were obtained by luteectomy during early (LH + 1 to 5 days, n = 3), midluteal (LH + 6 to 10 days, n = 3), and late (LH + 11 to 15 days, n = 4) luteal phases. MAIN OUTCOME MEASURE: Relative levels of messenger RNA for EGFR as determined by ribonuclease protection assay using RNA probe generated from complementary DNA for human EGFR. RESULTS: Messenger RNA for EGFR is present in baboon corpora lutea with relative levels of 0.51 +/- 0.18 (mean +/- SEM) in the early, 0.43 +/- 0.17 in the midluteal, and 0.50 +/- 0.17 arbitrary units in the late luteal phase. CONCLUSION: Baboon corpus luteum is a site of EGFR production; the levels of its messenger RNA did not change appreciably throughout the luteal phase.

Animals↗

Substrate spectrum of human excinuclease: repair of abasic sites, methylated bases, mismatches, and bulky adducts.

Nucleotide-excision repair is the repair system for removing bulky lesions from DNA. Humans deficient in this repair pathway suffer from xeroderma pigmentosum (XP), a disease characterized by photodermatoses, including skin cancers. At the cellular level, XP patients fail to remove cyclobutane pyrimidine dimers and pyrimidine(6-4)pyrimidone photoproducts induced by UV light, as well as other bulky DNA lesions caused by various genotoxic agents. XP cells are not particularly sensitive to ionizing radiation or to alkylating agents that cause mostly nonbulky DNA lesions. Therefore, it has generally been assumed that the human nucleotide-excision repair enzyme (excinuclease) is specific for bulky adducts. To determine the substrate range of human excinuclease we used the highly sensitive excision assay and tested bulky adducts, synthetic apurinic/apyrimidinic sites, N6-methyladenine, O6-methylguanine, and mismatches as potential substrates. We found that all of these "lesions" were removed by human excinuclease, although with vastly different efficiencies.

Animals↗

Human and E.coli excinucleases are affected differently by the sequence context of acetylaminofluorene-guanine adduct.

Synthetic DNA substrates containing an acetylaminofluorene (AAF) adduct at each of the three guanine in the G1G2CG3CC sequence were constructed and tested as substrates for reconstituted E.coli (A)BC excinuclease and human excinuclease in HeLa cell-free extract (CFE). The (A)BC excinulcease repaired the three substrates with relative efficiencies of G1:G2:G3 of 100:18:66 in agreement with an earlier report [Seeberg, E., and Fuchs, R.P.P. (1990) Proc. Natl Acad. Sci. USA 87, 191-194]. The same lesions were repaired by the human excinuclease with the strikingly different efficiencies of G1:G2:G3 as 38:100:68. These results reveal that the human excinuclease is affected by the sequence context of the lesion in a different manner than its prokaryotic counterpart.

Base Sequence↗

HMG-domain proteins specifically inhibit the repair of the major DNA adduct of the anticancer drug cisplatin by human excision nuclease.

The most frequent DNA adduct made by the anticancer drug cisplatin, the 1,2-intrastrand d(GpG) cross-link, as well as the minor 1,3-intrastrand d(GpTpG) adduct, were both repaired by an in vitro human excision repair system. Fragments of 27-29 nt containing the platinum damage were excised. The high mobility group (HMG)-domain proteins HMG1 and human mitochondrial transcription factor specifically inhibited repair of the 1,2-intrastrand cross-link by the human excision nuclease. These results suggest that the types and levels of HMG-domain proteins in a given tumor may influence the responsiveness of that cancer to cisplatin chemotherapy and they provide a rational basis for the synthesis of new platinum anticancer drug candidates.

Base Sequence↗

Determination of minimum substrate size for human excinuclease.

Human cells remove bulky adducts from DNA by excising single-stranded fragments 27-29 nucleotides in length by an enzyme system consisting of at least 14 polypeptides. All of the previous work on characterizing the excision reaction was conducted with plasmids 3 or 8 kilobases in length. To determine if the size and tertiary structure of DNA play a role in the excision reaction and to find out if large DNA fragments are necessary to contact all of the subunits of the excinuclease, we performed experiments with circular DNA and with linear DNA fragments of various sizes. We found that the human excinuclease is capable of removing DNA adducts from linear and covalently closed circular DNAs with about the same efficiency. Furthermore, we found that the excinuclease can remove a thymine dimer or a psoralen-thymine monoadduct from linear fragments provided that the distance between the lesion and the 5'-terminus of the damaged strand is > or = 60 nucleotides and the distance between the lesion and the 3'-terminus is > or = 44 nucleotides. Thus, the minimum size substrate for human excinuclease is approximately 100 base pairs in length.

Base Sequence↗