PubMed Health⌕ Search

Biomedical subjects

Y H Zhuang

Publications and source records attributed to Y H Zhuang.

At least 19 recordsLinked to original sources
PubMed2004

Combined DNA vaccines formulated in DDA enhance protective immunity against tuberculosis.

This study evaluated the adjuvant Dimethyldioctyldecyl Ammonium Bromide (DDA) effect on the protective immunity induced by a combination of plasmids containing genes encoding antigens Ag85B, MPT-83, and ESAT-6 from Mycobacterium tuberculosis. The combined DNA vaccines in DDA resulted in significant increases in both specific IgG and splenic T-cell-derived Th1-type cytokine gamma interferon (IFN-gamma) production in response to the three purified antigens when compared to that of combined DNA vaccines in saline. Vaccines in DDA increased the protective efficacy of mice challenged with M. tuberculosis H37Rv as measured by reduced relative CFU counts in their lungs. Mice immunized with the combined DNA vaccines were shown to limit the growth of tubercle bacilli both in lungs and in spleens. Histopathological analyses showed that vaccinated mice had substantially improved postinfection lung pathology relative to the controls. We suggest that our combination of antigens together with DDA formulation may provide a new insight into tuberculosis prevention.

Acyltransferases↗
PubMed2002

Phosphine and methane generation by the addition of organic compounds containing carbon-phosphorus bonds into incubated soil.

Formation of phosphine and methane in anaerobic incubation systems was investigated under stirred and unstirred conditions. The PH3 and CH4 levels in the headspace, as well as the matrix-bound PH3 content in the stirred soil, significantly increased upon the addition of phosphonoacetic acid (P(O)(OH)2CH2COOH). Both the levels of matrix-bound PH3 and CH4 are positively correlated to the buffered dithionite fraction of reactive phosphorus in the soil samples, while a negative correlation was observed between matrix-bound PH3/CH4 levels and the reactive phosphorus fraction.

Bacteria, Anaerobic↗
PubMed2001

Cell type-specific induction of cyclin D and cyclin-dependent kinase inhibitor p27(kip1) expression by estrogen in rat endometrium.

Cyclins, cyclin-dependent kinases (CDKs) and the CDK inhibitor p27(kip1) are known to be involved in the regulation of G(1)/S phase transition by estrogen in the rodent endometrium. Little is known, however, of the cell-specific location and regulation of these proteins during this process, or the way they mediate the differential effect of estrogen in the epithelium and stroma of the endometrium. Here we studied the cell-specific regulation of D-type cyclin (D(1-3)), of cyclin A and E, of CDK(2) and p27(kip1) by 17beta-estradiol in the endometrium of ovariectomized rats. Time-course changes in these proteins in the endometrium of ovariectomized rats were examined by immunohistochemistry at 2, 4, 8, 12, 20, 28 and 32 h after estrogen stimulation. The expression of proliferation cell nuclear antigen (PCNA) was also studied as a marker of proliferating cells. As expected from previous studies, all the proteins investigated were up-regulated by estrogen, with peak times from 8 to 32 h. The induction of cyclin D(1) is predominant in the glandular epithelium, whereas cyclin D(3) increases mainly in the luminal epithelium. The up-regulation of p27(kip1) is restricted to stromal cells with a 'gradient-like' expression pattern, in which the sub-epithelial (functional) layer showed stronger staining than the basal layer. The differential regulation of cyclins and p27(kip1) in the epithelium and stroma of the endometrium appear indicative of distinct actions of estrogen in different cell types in the uterus, as D-type cyclins mediate the proliferative effect of estrogen in epithelial cells while p27(kip1) might help prevent the same effect in the stroma.

Animals↗
PubMed2000

Phosphorus cycling through phosphine in paddy fields.

Phosphine emission fluxes from paddy fields, phosphine ambient levels in air, and the vertical profile of matrix-bound phosphine in soil have been measured throughout the growing season of rice in Beijing, China. It was found that both the seasonal and diurnal emission fluxes and ambient levels fluctuate significantly. During the drainage period, phosphine released from the soil with the highest diurnal average flux on the first period of drainage (approx. 17.7 ng m(-2) h(-1)), whereas its highest ambient level (approx. 250 ng m(-3)) occurred at 06.00 h. During the flooded period, phosphine emission was low, and the peaks of phosphine emissions occurred at midnight. The average flux of PH3 emission for the whole season was found to be approximately 1.78 ng m(-2) h(-1). The mass fraction of matrix-bound phosphine is approximately 0.18 approximately 1.42 x 10(-7) (m/m) part of organic phosphorus or 3.4 approximately 9.2 x 10(-9) (m/m) part of total phosphorus in paddy soil. The amount of phosphine emitted to the atmosphere was only a small fraction of the phosphine that remained in the soil in the matrix-bound form. Soil serves both as the source and the sink of PH3.

Air Pollutants↗
PubMed2000

Androgen receptor and vitamin D receptor in human ovarian cancer: growth stimulation and inhibition by ligands.

The data suggest that 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] and androgens are essential for regulation of growth and differentiation in, e.g., human reproductive tissues. We investigated the possible cross-talk between 1,25(OH)2D3 and androgens in the human ovarian cancer cell line OVCAR-3. Our data demonstrate that 1,25(OH)2D3 and androgen (dihydrotestosterone, DHT) regulate the growth of OVCAR-3 cells. Nine days' treatment of OVCAR-3 cells with 100 nM DHT resulted in 48% stimulation of growth, whereas growth inhibition (73%) was observed after treatment with 100 nM 1,25(OH)2D3. The combination of 1,25(OH)2D3 and DHT showed that 1,25(OH)2D3 clearly reduces the growth-stimulatory effect of DHT on OVCAR-3 cells. Moreover, Western blot analysis revealed that these cells contain receptors for 1,25(OH)2D3 (VDR) and androgen (AR). Expression of VDR and AR was up-regulated by their cognate ligands. Up-regulation of AR by 1,25(OH)2D3 and of VDR by DHT provides evidence of cross-talk between 2 signaling pathways in OVCAR-3 cells. We also studied the immuno-histochemical distribution of VDRs and ARs in rat ovaries and human ovarian cancer cases. In rat ovaries, VDRs were observed mainly in granulosa and theca cells and ARs in granulosa cells and surface epithelium. In the human ovarian cancer cases studied, 43% were VDR-positive and 64% AR-positive. Combining the results suggests that the growth of ovarian tissue might be regulated by 1,25(OH)2D3 and androgen.

Adenocarcinoma↗
PubMed1998

Evidence for enhanced ubiquitin-mediated proteolysis of the chicken progesterone receptor by progesterone.

Genomic actions of progesterone are mediated via A and B isoforms of the progesterone receptor (PR). One major factor controlling PR level is progesterone causing negative autoregulation (down-regulation) of the receptor protein. In this work we studied the mechanism whereby progesterone exerts its effects on PR level in the chicken oviduct. We found that progesterone does not markedly regulate PR mRNA expression. Furthermore, we demonstrate here for the first time that PR is a target for ubiquitylation and that the proportion of ubiquitylated PR is increased by progesterone treatment. Our data suggest that ligand-induced down-regulation of PR involves enhanced degradation of receptor protein by ubiquitin-proteasome system in vivo.

Amino Acid Sequence↗
PubMed1997

Expression of the chicken progesterone receptor forms A and B is differentially regulated by estrogen in vivo.

The chicken progesterone receptor (cPR), like its human counterpart (hPR), exists as two isoforms, PR-A and PR-B, displaying different biological activities depending upon cellular and promoter contexts. Here we show that the ratio of PR isoforms observed in the immature chicken oviduct is changed during estrogen-induced differentiation from PR-B dominancy to that of PR-A. This is the first report describing that the expression ratio of PR isoforms is altered by upregulation of PR-A by estrogen action in vivo. This result provides a plausible explanation to the differences in oviduct's response to progesterone depending on hormonal and developmental status of the animal.

Animals↗
PubMed1997

Spermatogenesis in the vitamin A-deficient rat: possible interplay between retinoic acid receptors, androgen receptor and inhibin alpha-subunit.

In order to understand the mechanisms of retinol action on the testis, testicular retinoic acid receptor alpha, beta(RAR alpha and beta), androgen receptor (AR) and inhibin alpha-subunit were studied in normal, vitamin A-deficient (VAD) and vitamin A-supplemented rats by immunohistochemistry and immunoblotting. Compared to the normal testis, expression of 110 K AR was up-regulated by vitamin A withdrawal, whereas 51 K RAR alpha remained unchanged. An additional 55 K RAR alpha signal was observed. Readministration of retinol caused a marked decrease of AR in the VAD testis. By 24 h, AR declined to below the normal level. Although the 51 K RAR alpha signal remained unchanged, the 55 K band was slightly up-regulated at 6 h after retinol administration. A 51 K RAR beta protein was seen in the VAD but in not the normal testis. The intensity of the 51 K RAR beta band remained constant before and after the administration of retinol, but it had a slight up-shift at 6 h after retinol injection, suggesting post-translational modification of the receptor. The inhibin alpha-subunit of 18 K protein was undetectable in the VAD testis and increased to above normal level at 24 h after retinol administration. Immunohistochemically, nuclear AR immunostaining was more intense in the VAD testis than in the normal testis. The intensity of immunostaining declined in all AR-positive cells after the injection of retinol, but the decrease was more evident in Sertoli than in other cells. At 24 h after retinol the immunostaining was undetectable in most Sertoli cells. The regulation of the inhibin alpha-subunit by retinol in the cytoplasm of Sertoli cells detected by immunohistochemistry was correlated to the results in immunoblotting. These results suggest a possible interplay between retinoids, androgen and inhibin signalling systems in Sertoli cells in the regulation of spermatogenesis during retinol action.

Animals↗
PubMed1997

Immunodetection of androgen receptor in human urinary bladder cancer.

We investigated the expression of androgen receptor (AR) protein in transitional cell carcinoma of human urinary bladder in paraffin-embedded sections of tumours obtained from nine patients with urinary bladder cancer treated by radical cystectomy. In addition, immunoblotting of AR was also performed on selected samples. Nuclear immunoreactivity of AR was found in seven of the nine urinary bladder cancers studied. AR showed variable staining intensity within a tumour. In the immunoblots, a 110 kDa AR signal was seen with anti-AR antibody, and faint bands of 90 and 60 kDa were also observed. Immunohistochemistry of p53 and c-erbB-2 was also carried out and compared with the distribution of AR. The high frequency of AR expression suggests a role for androgens in transitional cell carcinoma of human urinary bladder.

Adenocarcinoma↗
PubMed1997

Photoperiod-induced changes in androgen receptor expression in testes and accessory sex glands of the bank vole, Clethrionomys glareolus.

Photoperiodic modulation of androgen levels and androgen receptor (AR) expression in testes and accessory sex glands were studied in a seasonally breeding rodent, the bank vole. Juvenile voles subjected to long photoperiod (20L:4D) for 6-8 wk attained sexual maturity, which was associated with a prominent increase in testicular testosterone (T) levels and weight of testes and accessory sex glands. Pubertal development in short photoperiod-treated (6L:18D for 6-8 wk) juveniles was arrested, and subsequently reproductive regression set in with a marked decrease in testicular T levels and gonadal weight. In sexually active voles, strong AR immunostaining was detected in nuclei of epithelial, smooth muscle, and stromal cells of the epididymis, prostate, and seminal vesicles. In active testes, AR was present in nuclei of Sertoli cells, peritubular cells, Leydig cells, and vascular smooth muscle cells. In juveniles, strong to moderate nuclear immunoreactivity was encountered in epithelial and stromal cells of the epididymis and prostate, whereas a weaker reaction was discerned in seminal vesicles. In juvenile testes, AR was localized to vascular smooth muscle cells, peritubular, and interstitial cells. In sexually regressed animals, nuclear staining was almost absent in accessory sex glands, whereas in testes, moderate immunostaining was retained in all other cell types except the Sertoli cells. Western blots of active and regressed testes indicated a marked photoperiod-induced down-regulation of immunodetectable AR in the regressed gonad.

Aging↗
PubMed1996

Androgen receptor in rat Harderian and submandibular glands.

Androgens regulate the development and sexual dimorphism of rodent Harderian and submandibular glands. This effect is believed to be mediated by the androgen receptor. Immunohistochemistry and immunoblotting were carried out to study the receptor in normal, castrated and dihydrotestosterone-supplemented rat Harderian and submandibular glands. Immunohistochemically, the most intense nuclear staining was observed in the acinar cells of the submandibular glands, followed by intercalated duct cells. The granular convoluted tubules showed weak immunostaining and the striated ducts were negative. In the Harderian gland, nuclear staining was seen in both type I and II secretory cells. Castration and treatment had no effect on the expression of the androgen receptor protein in either gland. A 110 K androgen receptor signal was detected by immunoblotting in the Harderian gland but not in the submandibular gland. An experiment was designed to explore the possible effect of proteinases on the receptor protein in the homogenate of submandibular gland. Our results demonstrate the cell-specific location of the receptor in Harderian and submandibular glands, and show that the expression of the receptor protein is androgen-independent.

Animals↗
PubMed1996

Immunochemical and in situ hybridization analyses of retinoic acid receptor alpha, beta, and gamma in murine Harderian and submandibular glands.

Retinoic acid (RA), through its cognate receptors (retinoic acid receptors, RARs), plays an important role in the ontogenesis and maintenance of the normal function of murine Harderian and submandibular glands. In the present study, autoradiography was used to study RA binding to these glands. Both glands showed high radioactive labelling after [14C]-RA administration in normal and partially vitamin A-deficient (VAD) mice. The peak uptake was at 6 h after [14C]-RA administration in normal mice and at 0.5 h in VAD mice. At 24 h, RA binding remained high in normal mice, while it decreased significantly in VAD mice. In western blots with an antibody recognizing all forms of RARs, a band of molecular weight 51 kDa was seen in homogenates of both glands. Immunohistochemically, RAR staining was found in the nuclei of the glandular cells. The Harderian gland exhibited more intense staining than the submandibular gland. In the latter, the most intense staining was seen in the acinar cells, followed by the intercalated duct cells. The granular convoluted tubule showed weak immunostaining and the striated duct was negative. In the Harderian gland, RAR immunostaining was observed in both type I and II cells, but only part of them stained with RAR antibody. The expression of RAR alpha, beta, and gamma transcripts was studied by in situ hybridization using specific oligonucleotide probes. The cell-specific expression of RAR alpha mRNA in the submandibular gland corresponded to the RAR proteins detected by immunohistochemistry, while the RAR beta transcript was mainly seen in the striated duct. The transcripts of RAR alpha and beta were evenly distributed in type I and II glandular cells of the Harderian gland. RAR gamma labelling was below detectable levels in both glands. This result suggests that RA and RARs regulate the functions of Harderian and submandibular glands in a cell-specific manner.

Animals↗
PubMed1996

Mechanisms of action of sex steroid hormones: basic concepts and clinical correlations.

The review deals with the clinically important aspects of the basic mechanisms of sex steroid hormones. Steroids can act through two basic mechanisms: genomic and non-genomic. The classical genomic action is mediated by specific intracellular receptors, whereas the primary target for the non-genomic one is the cell membrane. Many clinical symptoms seem to be mediated through the non-genomic route. Furthermore, membrane effects of steroid and other factors can interfere with the intranuclear receptor system inducing or repressing steroid-and receptor-specific genomic effects. These signalling pathways may lead to unexpected hormonal or anti-hormonal effects in patients treated with certain drugs. Steroid receptors (SRs) are members of a large family of nuclear transcription factors that regulate gene expression by binding to their cognate steroid ligands, to the specific enhancer sequences of DNA (steroid response elements) and to the basic transcription machinery. SRs are phosphoproteins, which are further phosphorylated after ligand binding. The role of phosphorylation in receptor transaction is complex and may not be uniform to all SRs. However, phosphorylation/dephosphorylation is believed to be a key event regulating the transcriptional activity of steroid receptors. SR activities can be affected by the amount of SR in the cell nuclei, which is modified by the rate of transcription and translation of the SR gene as well as by proteolysis of the SR protein. There is an auto- and heteroregulation of receptor levels. Some of the SRs appear to bind specific protease inhibitors and exhibit protease activity. The physiological significance of this weak proteolytic activity is not clear. Some SRs are expressed as two or more isoforms, which may have different effects on transcription. Receptor isoforms are different translation or transcription products of a single gene. Isoform A of the progesterone receptor is a truncated form of PR isoform B originating from the same gene, but it is able to suppress not only the gene enhancing activity of PR-B but also that of other steroid receptors. From the clinical point of view, it is important to note that the final hormonal effect in a target tissue is dependent on the cross talk between different nuclear steroid receptors and on expression of receptor isoforms.

Animals↗
PubMed1995

Distribution of all-trans-retinoic acid in normal and vitamin A deficient mice: correlation to retinoic acid receptors in different tissues of normal mice.

The distribution of all-trans-retinoic acid (RA) was investigated using whole-body autoradiography of normal and partial vitamin A deficient (VAD) mice. Retinoic acid receptors (alpha, beta, and gamma) were also studied in normal mice using immunoblotting. Normal and VAD mice were injected with 5 muCi 14C RA. The distribution of RA was quantitatively studied using a computer-assisted image analysis system. 14C RA was incorporated 0.5 hr after RA administration in both normal and VAD mice, while the labelling peak was at 6 hr in most organs in normal and VAD mice. The most intense labeling was found in liver, kidney, intestine, lung, Harderian gland, and salivary gland at all time points. A band of M(r) 51K was found in all mouse tissues by immunoblotting using the polyclonal antibody RAR82 against total RARs or the RAR alpha-specific monoclonal antibody R alpha 13. In some tissue, an additional band of 55-58K was also found. Lung, large intestine, small intestine, testis, seminal vesicle, and spleen contained highest concentration of total RARs, while heart, lung, small intestine, spleen, salivary gland, and preputial gland had the highest concentration of RAR alpha. The uptake of labeled RA correlated well with RAR or RAR alpha concentration in the corresponding tissues.

Animals↗
PubMed1994

Immunolocalization of retinoic acid receptors in rat, mouse and human ovary and uterus.

We raised an antibody against a synthetic peptide corresponding to amino acids 155-174 of human retinoic acid receptor alpha (RAR-alpha). The sequence is highly homologous in all RARs and their isoforms. When mouse and human RARs (alpha, beta and gamma) expressed in Cos cell were analysed with immunoblot, all receptors gave a specific 51 K signal. Mouse RAR-gamma gave an additional signal corresponding to 58 K. In human teratocarcinoma cells (F9) both 51 and 58K molecule sizes were detected. The RAR expression in F9 cells was slightly down-regulated in charcoal-stripped culture medium and returned to normal level after retinoic acid treatment. The 51 K protein was found in all ovarian and uterine samples, but the quantity of the 58 K protein varied in different species and organs, being highest in the mouse uterus and the rat and human ovary. Using immunohistochemistry the RARs were found in the nuclear compartment. In the rat uterus, positive immunoreaction was found mainly in the nuclei of epithelial, uterine glandular and stromal cells. In the rat ovary, positive reaction was found in the nuclei of germinal epithelial, follicular and stromal cells.

Amino Acid Sequence↗
PubMed1993

Immunohistochemical localization of the avian progesterone receptor and its candidate receptor binding factor (RBF-1).

An avian oviduct nuclear matrix protein in the 6-10 kDa size range has been implicated to function in the cell-free nuclear binding of the avian oviduct progesterone receptor (PR). This protein, termed the receptor binding factor-1 (RBF-1), has been purified and partially characterized [Schuchard et al.: Biochemistry 30:4535-4542, 1991]. This paper describes the immunohistochemical co-localization of the RBF-1 and PR in the avian oviduct cell nuclei and rat reproductive cell nuclei using antibodies directed specifically against the RBF-1 and activated PR. In the undifferentiated oviduct, the immunoreactivities for both PR and RBF-1 were co-localized in the nuclei of only epithelial cells, but not the stromal cells or smooth muscle cells. In the partially differentiated oviduct of estrogen treated chicks, the immunoreactivity co-localized in the nuclei of not only epithelial but also glandular and stromal cells. Staining for the PR, but not RBF-1, was detected in the smooth muscle cells. The intensity of the PR but not the RBF-1 staining was markedly down-regulated in these cells at 2 and 6 h after treatment of the animals with progesterone (P). However, the band patterns for RBF-1 in the Western blots did show qualitative changes which may reflect P-induced posttranslational modifications which alter the epitope on the RBF-1. Interestingly, immunohistochemical analysis of several reproductive tissues of the rat showed that certain cell types in the uterus, ovary, and prostate displayed strong positive nuclear staining for an RBF-1-like antigen(s).(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗