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W Huang

Publications and source records attributed to W Huang.

At least 595 records · Page 33Linked to original sources
PubMed1993

Postnatal development of the rat CNS following in utero exposure to a low dose of ionizing radiation.

In utero exposure to ionizing radiation is of importance because of its potential health risks. The developing nervous system is particularly vulnerable and the consequences of exposure to low levels of radiation (< or = 1 Gy) are not well established. The developmental effects of maternal exposure to 50 cGy gamma-radiation on gestational days (GD) 9.5, 15, and 18 were investigated in Sprague Dawley rats. Rats exposed on GD-9.5 along with appropriate controls were killed at 4 h, 48 h, and 10 days post-irradiation while those irradiated on GD-15 and GD-18 were killed postnatally (PN) on days 7 and 26. All were examined for developmental anomalies and representative samples of brains were processed for microscopic study. No significant developmental differences were observed between irradiated and control embryos killed 48 h after irradiation on GD 9.5. However, in irradiated fetuses a larger number of developmental anomalies were observed at term. Defects of the eye and of spinal curvature were the most common malformations encountered. Mitoses were reduced within the neuroepithelium of embryos irradiated on GD-9.5 and evidence of pyknosis and necrosis was seen 4 h after irradiation. The capacity of surviving primitive neural cells for repair, however, was such that by 48 h after exposure the irradiated nervous system no longer differed from controls. Rats irradiated on GD-15 and GD-18 and examined on PN-26 exhibited clusters of small, dark, pyknotic neurons within the hippocampal and dentate gyri, often bilaterally.(ABSTRACT TRUNCATED AT 250 WORDS)

Abnormalities, Radiation-Induced↗
PubMed1993

Immunoassay detection of nordiazepam, triazolam, lorazepam, and alprazolam in blood.

The ability of commercial benzodiazepine immunoassays to detect nordiazepam, lorazepam, alprazolam, and triazolam in blood samples was investigated. Two radioimmunoassays (RIA) (Abuscreen [RIA-a] and the Diagnostic Products Corporation serum kit [RIA-d]), two enzyme immunoassays (EIA) (Emit d.a.u. [EIA-u] and Emit TOX serum assay [EIA-s]), and two fluorescence polarization immunoassays (FPIA) (X-systems urine [FPIA-u] and X-systems serum assay [FPIA-s]) were evaluated for their ability to detect benzodiazepines in fortified drug-free human or bovine blood. Prior extraction of the blood was necessary for analysis on the equipment used for EIA and FPIA. Extraction with an organic solvent, such as butyl chloride used in this study, was preferable to precipitation with methanol or zinc sulfate. For all these assays, extraction eliminated matrix effects and offered the possibility of increased sensitivity by reconstitution of the extract in a smaller volume. Extraction was necessary in bovine blood, as there is some nonextractable substance(s) in this matrix that increases non-specific binding. Using extraction with reconstitution in one-half the original volume, the apparent limit of detection for nordiazepam in blood ranged from 3 ng/mL, with RIA-d, to 30 ng/mL, with EIA-s and FPIA-s. These limits of detection were improved by further reduction of the reconstitution volume. RIA-a, EIA-s, and FPIA-s had cross-reactivity for alprazolam that was equivalent to or slightly better than nordiazepam. RIA-d had enhanced cross-reactivity for alprazolam at 30-300 ng/mL.(ABSTRACT TRUNCATED AT 250 WORDS)

Alprazolam↗
PubMed1993

The adenylyl cyclase-cyclic AMP system modulates morphological and functional development of hypothalamic beta-endorphin neurons in culture.

In rats, opioidergic beta-endorphin (beta EP1-31) is produced and released from neurons of arcuate nuclei in the hypothalamus. Although the neuropeptide has been implicated in sexual maturation and stress-induced reproductive dysfunction, the intra-hypothalamic regulation of beta EP neurons remains unclear. Employing long-term monolayer cultures of neonatal rat hypothalamic cells, we report here that 4 days of treatment with 10 microM forskolin increased approximately 3-fold (P < 0.01) the proportion of immunoreactive (ir)-beta EP positive neurons bearing neurites. In addition, treatment of forskolin also enhanced ir-beta EP release (634 +/- 59 pg/well; mean +/- SE, n = 4, P < 0.01) by 14-fold and ir-beta EP content (119 +/- 13 pg/well; P < 0.01) by 2-fold above that of vehicle-treated cultures; in both instances, the EC50 and the Emax of forskolin were approximately 10 microM and 100 microM, respectively. The forskolin-stimulated release of ir-beta EP was mimicked by cholera toxin and (Bu)2cAMP treatment in a dose-related manner, but not by pertussis toxin. Although by itself 3-isobutyl-1-methyl-xanthine (100 microM) only doubled ir-beta EP secretion, it markedly potentiated the stimulatory effect of forskolin. This forskolin-induced stimulation was reversible and in cultures re-exposed to the same drug within the first 24 h period, there was a marked increase in the stimulated release of ir-beta EP (P < 0.05); re-challenge of forskolin at later stages, however, induced a smaller but significant secretion of ir-beta EP (P < 0.01) compared to that of vehicle-treated control cultures. Sephadex G-50 gel chromatographic profile of the media prepared from forskolin-treated cultures revealed a major ir-beta EP peak of 3 K M(r). High-performance liquid chromatography analysis showed that ir-beta EP of the 3 K M(r) species was eluted with a retention time similar to that of synthetic rat beta EP1-31. We thus conclude that the adenylyl cyclase-cAMP system plays an important role in the modulation of beta EP1-31 production and release from hypothalamic beta EP neurons in culture. Furthermore, the functional responsiveness and the morphological development of these neurons are affected, at least in part, by the intrinsic activity of the adenylyl cyclase-cAMP system.

1-Methyl-3-isobutylxanthine↗
PubMed1993

Ascorbic acid enhances forskolin-induced cyclic AMP production and pro-ANF mRNA expression of hypothalamic neurons in culture.

Besides acting as an important cofactor in the biosynthesis of catecholamine, ascorbic acid (AA) also modulates the activity of peptidyl-glycine alpha-amidating monooxygenase for the post-translational modification of neuropeptides such as alpha-MSH and TRH. We report here a novel action of AA in modulating the secretion and mRNA expression of atrial natriuretic factor (ANF) in rat hypothalamic neurons. Primary cultures of hypothalamic neurons from neonatal rats as previously described were employed in the present studies. Six days after plating, cultures were replenished with serum free media and incubated with vehicle or various doses of AA, alone or in the presence of forskolin. Treatment with AA alone significantly increased irANF secretion from the cultures in a time-related and a dose-dependent manner with an ED50 of approximately 3 microM and an Emax of 100 microM. At the concentration of 10 microM, AA augmented irANF release approximately 3 fold that of the controls (55 +/- 7 pg/well; mean +/- SE, n = 3; P < 0.01), but it failed to affect the abundance of pro-ANF mRNA in the cultures. However, 10 microM of AA markedly enhanced forskolin-induced irANF secretion and pro-ANF mRNA abundance of the cultured cells. This potentiating effect of AA on forskolin stimulation showed a good parallelism to the levels of cAMP produced in the hypothalamic cultures. We thus conclude that AA acts alone or in synergism with forskolin to stimulate the secretion and production of ANF in rat hypothalamic neurons; this latter effect may operate at the genomic level and is mediated, at least in part, through the protein kinase A dependent pathway.

Animals↗
PubMed1993

In vitro evidence for atrial natriuretic factor-(5-28) production by macrophages of adult rat thymi.

Although recent evidence suggests the presence of the 15-kilodalton (K) mol wt (Mr) precursor of atrial natriuretic factor (ANF) and pro-ANF mRNA in the thymus of human and rat neonates, the cellular origin of the peptides in the tissues remains to be elucidated. We report here that in adult male rats, the 15K M(r) presumptive precursor for ANF and a smaller 3K M(r), N-terminal truncated congener of the peptide, ANF-(5-28), are localized in a small population of thymic macrophages. The production of ANF in the thymus was further confirmed by demonstrating the presence of a single band of pro-ANF mRNA signal of approximately 0.8 kilobases from the tissue extract, corresponding to that in the heart. To examine the distribution of pro-ANF mRNA at a cellular level, colorimetric in situ hybridization with digoxigenin-labeled 30-mer oligonucleotides complementary to the first 10-amino acid sequence of ANF-(1-28) was employed. Positive staining was found in thymic cells localized mainly in subcapsular areas, with diffuse staining of positive cells in both the cortex and medulla mainly concentrated around the cortico-medullary junction of the tissue. The identity of the ANF-positive cells was further investigated using a double staining technique to costain immunoreactive (ir) ANF and the macrophage markers ED1 and S22 or the T-cell marker OX-19 in both thymic sections and in monolayer cultures of thymic cells. In the latter, approximately 17% of the adherent cells stained positive for irANF after 48 h in culture. Of these cells, more than 95% also stained positive for the macrophage marker ED1, whereas approximately 36% of the ED1-positive cells were colocalized with irANF. In contrast, no irANF-positive cells were colocalised with the pan-T-cell marker OX-19. In tissue sections, irANF was found in cells distributed predominantly around the cortico-medullary junctions and subcapsular areas, with diffuse staining of the cells in the medullary and cortical regions. Sephadex G-50 gel chromatographic profiles of thymic extracts revealed a major peak of immunoreactivity consistent with 15K M(r) and a smaller peak that coeluted with rat ANF-(1-28) of 3K M(r). HPLC analysis of the 3K M(r) species showed a single peak of immunoreactivity, which eluted with a retention time identical to that of synthetic rat ANF-(5-28).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1993

Coexpression of atrial natriuretic factor and beta-endorphin in a subpopulation of rat splenic macrophages: age-related differences.

Separate demonstration of immunoreactive (ir) atrial natriuretic factor (ANF) and ir-beta-endorphin (beta EP) in macrophages of the rat spleen prompted a reexamination of their distribution and cellular localization in addition to their developmental regulation. Double labeling immunohistochemistry was carried out on paraffin-embedded spleen sections of adult male Sprague-Dawley rats. Cells stained positive with antiserum (S118) raised against rat ANF-(99-126) were colocalized in more than 95% of cases with immunofluorescent staining of ir beta EP-(1-31) and distributed sparsely throughout the venous sinusoidal regions of the red pulp. In 1- or 5-day monolayer cultures of adherent splenocytes, 11-16% of the cells stained positive for either irANF or ir beta EP. Under these conditions, more than 95% of irANF- and ir beta EP-positive cells were also fluorescence stained for the histiocyte marker S22 or the rat macrophage marker ED-1. Colorimetric in situ hybridization similarly revealed signals for pro-ANF mRNA in more than 95% of ir beta EP-positive adherent cells. Thus, taken together with previous reports, our present findings suggest that in the rat spleen, both ANF and beta EP are produced by the same population of macrophages. However, the tissue levels and processing of the two peptides over the developmental period of the animal differed markedly in several ways. In splenic extracts of 2-day-old neonatal rats, Northern blot analysis and RIA revealed a greater abundance of pro-ANF mRNA signal and an irANF concentration about 6-fold greater than those in 30-day-old animals. In contrast, the ir beta EP concentration did not vary significantly over the same period, consistent with the level of POMC mRNA. Sephadex G-50 gel chromatography of splenic extracts from 2-day-old animals revealed predominantly higher mol wt forms of irANF and ir beta EP. From days 16-60, a significant proportion of irANF eluted in the same fractions as the mature circulating form, rat ANF-(99-126); the proportion of 3.5-kilodalton ir beta EP increased progressively to become the predominant species in adult tissues. Thus, it appears that although ANF and beta EP are coexpressed by the same population of splenic macrophages, they differ markedly during the developmental period with respect to their constitutive regulation.

Aging↗
PubMed1993

Problems existing in differentiation therapy of acute promyelocytic leukemia (APL) with all-trans retinoic acid (ATRA).

A large number of acute promyelocytic leukemia (APL) patients, treated with all-trans retinoic acid (ATRA) and chemotherapy, were studied. The results of the studies are as follows: (1) Among 65 patients investigated for the postremissional therapy, the 5-year survival probabilities were 0.20 +/- 0.13 (mean +/- SE) in the group treated with ATRA alone, 0.47 + 0.10 (mean +/- SE) in the group using chemotherapy alone and 0.42 +/- 0.09 (mean +/- SE) in the group treated with chemotherapy and ATRA. (2) The main severe adverse effects in the ATRA treatment include retinoic acid syndrome, renal failure, and thrombosis. These sequelae were observed more frequently in cases with persistent, marked elevation of white blood cell count without significant maturation of leukemic promyelocytes. (3) APL is not a homogeneous disease in that among 50 patients studied at the molecular level, although a PML-RARA fusion gene was detected in 45 cases, one had a variant translocation t(11;17) bearing fusion gene PLZF-RARA, one presented no obvious structural alteration of the PML gene while the RARA gene was rearranged, and three patients had no rearrangement of either PML or RARA genes. (4) Using RT/PCR to detect minimal residual disease, we found positive rates of 22%, 18.4%, and 11.5%, respectively, 12, 24, and 36 months after CR. This observation justifies the use of chemotherapy for at least 3 years after CR induced by ATRA. (5) It seems likely that the fusion gene PML-RARA plays an important role in APL leukemogenesis and in its response to the ATRA treatment.

Actuarial Analysis↗
PubMed1993

Expression levels of IL-6 mRNA in PBMNCs from patients with IDDM, NIDDM and normals by RT-PCR procedure.

Although it has been confirmed that insulin dependent diabetes mellitus (IDDM) is a kind of autoimmune disease, islet cell autoantibodies (ICAs), insulin autoantibodies (IAA) and anti-GAD-glutamic acid decardaxylase antibodies have been found in the sera of patients with IDDM and immunotherapies have been used in some patients with IDDM, yet the manner in which the dysfunctional immunosystem acts on beta cells and causes damage to them remains to be clarified. Recently, possible involvement of the abnormal production of IL-6 in autoimmune symptoms was suggested in patients with cardiac myxomas, Castleman's disease and rheumatoid arthritis. However reports of IL-6 abnormal production in patients with IDDM are rare. In the present study, we examined whether or not an abnormal expression of IL-6 mRNA was present in mononuclear cells (PBMNCs) of the peripheral blood of patients with IDDM. We devised a highly sensitive, specific and semiquantitative protocol, ie, reverse transcription and polymerase chain reaction (RT-PCR). We have used such an assay to measure the relative expression levels of IL-6 mRNA in PBMNCs from 12 early IDDM patients (duration < 6 mon, 8.20 +/- 3.85 yr), 29 newly-diagnosed NIDDM patients (54.85 +/- 9.12 yr), 23 normal children (8.20 +/- 3.26 yr) and 12 normal adults (31.92 +/- 11.22 yr). In this assay significantly high expression levels of IL-6 mRNA were found in PBMNCs from patients with IDDM (P < 0.05). The relative levels were 0.91 +/- 0.19; 0.10 +/- 0.06; 0.43 +/- 0.08; 0.10 +/- 0.07, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Molecular study on the chromosome 15 breakpoints in the translocation t(15; 17) in acute promyelocytic leukemia (APL).

Chromosomal translocation t(15; 17) is a specific marker of acute promyelocytic leukemia (APL). In this study, molecular cloning of the t(15; 17) breakpoint was carried out in a Chinese APL patient. It has been shown that the retinoic acid receptor alpha (RARA) gene, normally located on chromosome 17, was fused with a new transcription unit PML, normally localized on chromosome 15. We have subsequently cloned a portion of the PML gene and generated a panel of probes. A PML gene rearrangement was detected in 33 out of 36 APL cases studied. 24 rearrangements were clustered in a 4.4 kb region, designated here as PMLbcr1 whereas 9 rearrangements were concentrated in a 6.5 kb region, defining another breakpoint cluster region (PMLbcr2). These two types of rearrangement constitute the basis for the heterogeneity of the PML-RARA fusion gene and its possible biological significance remains to be explored.

Adolescent↗
PubMed1992

Catalytic properties of the human cytochrome P450 2E1 produced by cDNA expression in mammalian cells.

A full-length cDNA encoding human cytochrome P450 2E1 was expressed in mammalian cell lines using the vaccinia virus expression system. Immunoblot analysis showed that the expressed protein reacted with a polyclonal antibody against rat 2E1 and comigrated with P450 2E1 from human liver microsomes. P450 2E1 expressed in Hep G2 cells, a human cell line which contains both cytochrome b5 and NADPH:P450 oxidoreductase, was able to metabolize several known P450 2E1 substrates: N-nitrosodimethylamine (NDMA), N-nitrosomethylbenzylamine (NMBzA), p-nitrophenol, phenol, and acetaminophen. Apparent Km and Vmax values for NDMA demethylation were 22 microM and 173 pmol/min/mg microsomal protein, respectively. P450 2E1 expressed in TK-143 cells, which do not contain b5, displayed Km and Vmax values of 31 microM and 34 pmol/min/mg microsomal protein, respectively. Incorporation of purified rat liver b5 into TK-143 microsomes increased the Vmax 2.2-fold and decreased the Km to 22 microM. Addition of b5 to Hep G2 microsomes resulted in a 1.6-fold increase in Vmax, but showed no effect on the Km. P450 2E1 expressed in Hep G2 cells was shown to metabolize NMBzA with a Km of 47 microM and Vmax of 213 pmol/min/mg microsomal protein. Addition of b5 lowered the Km to 27 microM, but had no effect on Vmax. These results demonstrate conclusively that P450 2E1 is responsible for the low Km forms of NDMA demethylase and NMBzA debenzylase observed in liver microsomes and that these activities are affected by cytochrome b5.

Animals↗
PubMed1992

Macromolecular assemblage in the design of a synthetic AIDS vaccine.

We describe a peptide vaccine model based on the mimicry of surface coat protein of a pathogen. This model used a macromolecular assemblage approach to amplify peptide antigens in liposomes or micelles. The key components of the model consisted of an oligomeric lysine scaffolding to amplify peptide antigens covalently 4-fold and a lipophilic membrane-anchoring group to further amplify noncovalently the antigens many-fold in liposomal or micellar form. A peptide antigen derived from the third variable domain of glycoprotein gp120 of human immunodeficiency virus type 1 (HIV-1), consisting of neutralizing, T-helper, and T-cytotoxic epitopes, was used in a macromolecular assemblage model (HIV-1 linear peptide amino acid sequence 308-331 in a tetravalent multiple antigen peptide system linked to tripalmitoyl-S-glycerylcysteine). The latter complex, in liposome or micelle, was used to immunize mice and guinea pigs without any adjuvant and found to induce gp120-specific antibodies that neutralize virus infectivity in vitro, elicit cytokine production, and prime CD8+ cytotoxic T lymphocytes in vivo. Our results show that the macromolecular assemblage approach bears immunological mimicry of the gp120 of HIV virus and may lead to useful vaccines against HIV infection.

AIDS Vaccines↗
PubMed1992

Inactivation of the protein phosphatase 2A regulatory subunit A results in morphological and transcriptional defects in Saccharomyces cerevisiae.

We have determined that TPD3, a gene previously identified in a screen for mutants defective in tRNA biosynthesis, most likely encodes the A regulatory subunit of the major protein phosphatase 2A species in the yeast Saccharomyces cerevisiae. The predicted amino acid sequence of the product of TPD3 is highly homologous to the sequence of the mammalian A subunit of protein phosphatase 2A. In addition, antibodies raised against Tpd3p specifically precipitate a significant fraction of the protein phosphatase 2A activity in the cell, and extracts of tpd3 strains yield a different chromatographic profile of protein phosphatase 2A than do extracts of isogenic TPD3 strains. tpd3 deletion strains generally grow poorly and have at least two distinct phenotypes. At reduced temperatures, tpd3 strains appear to be defective in cytokinesis, since most cells become multibudded and multinucleate following a shift to 13 degrees C. This is similar to the phenotype obtained by overexpression of the protein phosphatase 2A catalytic subunit or by loss of CDC55, a gene that encodes a protein with homology to a second regulatory subunit of protein phosphatase 2A. At elevated temperatures, tpd3 strains are defective in transcription by RNA polymerase III. Consistent with this in vivo phenotype, extracts of tpd3 strains fail to support in vitro transcription of tRNA genes, a defect that can be reversed by addition of either purified RNA polymerase III or TFIIIB. These results reinforce the notion that protein phosphatase 2A affects a variety of biological processes in the cell and provide an initial identification of critical substrates for this phosphatase.

Amino Acid Sequence↗
PubMed1992

Oxygen dissociation curve in the adult respiratory distress syndrome.

The oxygen tension for half saturation (P50) was determined for venous blood in thirteen patients with the adult respiratory distress syndrome undergoing intensive therapy. The mean value for P50 was found to be significantly lower than the value found in ten normal control subjects (22.9 mmHg and 26.7 mmHg respectively; t = 3.03, P < 0.01). The extent of reduction in P50 was not related to serum phosphate level nor was it a predictor of short-term outcome. It is unlikely that the slight left-shifted oxygen-haemoglobin dissociation curve contributes in a major way to an oxygen delivery deficiency and its cause is unexplained.

Adult↗
PubMed1992

Norepinephrine stimulates immunoreactive (ir) atrial natriuretic peptide (ANP) secretion and pro-ANP mRNA expression from rat hypothalamic neurons in culture: effects of alpha 2-adrenoceptors.

Although ANP or its smaller congeners are produced and secreted from rat hypothalami, the role or roles of neurotransmitter(s) in regulating their release and production from the neurons remains unclear. We report here that norepinephrine or epinephrine (NE/EPI) facilitates irANP secretion and pro-ANP mRNA expression in long term cultures of rat hypothalamic neurons through their effects on alpha 2-adrenoceptors. Hypothalami of 3 day-old Sprague-Dawley rats were removed and digested with collagenase. The dispersed cells were plated on poly-D-lysine coated culture dishes (10(6) cells/well) in Hepes buffered Dulbecco's Modified Eagle Medium supplemented with 8% fetal calf serum. Six days after plating, media were replenished with serum free media and the cultures incubated for 4 more days with vehicle or various doses of NE, EPI, alpha- or beta-adrenoceptor agonists in the presence of absence of antagonists. Culture media were then extracted with C18 Sep-pak and the levels of irANP determined by a well characterised RIA for ANP. NE or EPI treatment significantly increased irANP secretion from the cultures in a dose related manner with ED50 and Emax of approximately 0.2 microM and 1 microM respectively. The stimulation effect of NE was blocked by yohimbine (alpha 2-antagonist), but not prazosin (alpha 1-antagonist) or propranolol (beta-antagonist). Clonidine (alpha 2-agonist), but not phenylephrine (alpha 1-agonist) or isoprenaline (beta-agonist) mimicked the effects of NE or EPI. At the concentration of 0.1 microM, clonidine increased irANP release approximately 3 fold above that of control values (34.7 +/- 3.3; mean +/- SE, n = 4). These changes were accompanied by corresponding increments in the abundance of pro-ANP mRNA in the cultures as examined by a colorimetric Northern blot analysis. Our results indicate that NE or EPI, acting through its alpha 2-adrenoceptors, may modulate the function of ANP neurons in rat hypothalami by regulating the secretion and production of the neuropeptide at the genomic level.

Animals↗