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Biomedical subjects

L Zhuang

Publications and source records attributed to L Zhuang.

At least 55 records · Page 3Linked to original sources
PubMed1997

Depressed Langerhans cell migration and reduced contact hypersensitivity response in mice lacking TNF receptor p75.

Epidermal Langerhans cells (LC) belong to the dendritic cell family and represent the major APC within the skin. LC capture epicutaneous Ag, migrate into regional lymph nodes, and present Ag to T cells, thereby initiating primary immune response. The migratory properties of LC are an essential component of their function. The molecular mechanisms responsible for LC migration are far less defined. However, evidence has been accumulating to suggest that TNF-alpha, a major proinflammatory cytokine, plays an important role in promoting DC migration. To confirm the role of TNF-alpha in LC migration and to examine which type of TNF receptor signaling is involved in such an event, we utilized gene-targeted knockout mice lacking TNF receptor p55 or p75. The migration of LC was assessed by examining the frequency of hapten-bearing cells in draining lymph nodes following hapten FITC painting, and the accumulation of dendritic cells in draining lymph nodes after intradermal injection of TNF-alpha. While LC migration was normal in p55-deficient mice, the migration was markedly depressed in p75-deficient mice. Receptor p75-deficient mice also demonstrated a hyporesponsiveness in allergen-induced contact dermatitis, but a normal responsiveness in irritant-induced contact dermatitis. These results suggest that p75-dependent signaling plays a crucial role in the migration of LC and in the initiation of cutaneous immune responses.

Administration, Cutaneous↗
PubMed1997

Steroidogenic factor-1 is an essential transcriptional activator for gonad-specific expression of promoter I of the rat prolactin receptor gene.

The expression of the prolactin receptor is under the control of two putative tissue-specific (PI, gonads; PII, liver) and one common (PIII) promoters (Hu, Z. Z., Zhuang, L., and Dufau, M. L. (1996) J. Biol. Chem. 271, 10242-10246). The three promoter regions were co-localized to the rat chromosomal locus 2ql6, in the order 5'-PIII-PI-PII-3'. To investigate the mechanisms of gonad-specific utilization of PI, the promoter domain, regulatory cis-elements, and trans-factors were identified in gonadal cells. The promoter domain localized to the 152-base pair 5' of the transcriptional start site at -549 is highly active in gonadal cells but has minimal activity in hepatoma cells. It contains a steroidogenic factor 1 (SF-1) element (-668) that binds the SF-1 protein of nuclear extracts from gonadal cells and is essential for promoter activation. A CCAAT box (-623) contributes minimally to basal activity in the absence of the SF-1 element, and two adjacent TATA-like sequences act as inhibitory elements. Thus, PI belongs to a class of TATA-less/non-initiator gene promoters. These findings demonstrate an essential role for SF-1 in transcriptional activation of promoter I of the prolactin receptor gene, which may explain the tissue-specific expression of PI in the gonads but not in the liver and the mammary gland.

Animals↗
PubMed1997

Increased plasma serotonin following treatment with flavone-8-acetic acid, 5,6-dimethylxanthenone-4-acetic acid, vinblastine, and colchicine: relation to vascular effects.

A number of antitumor agents are known to cause selective reduction in tumor blood flow, leading in some cases to tumor necrosis and growth delay. These agents include flavone acetic acid (FAA), an antitumor agent with high experimental but no clinical antitumor activity, 5,6-dimethylxanthenone-4-acetic acid (DMXAA), a highly active analogue of FAA, endotoxin, vinblastine, and colchicine. We find here that plasma concentrations of serotonin (5-hydroxytryptamine) and its metabolite 5-hydroxyindole acetic acid (5-HIAA) are increased following administration of these agents. Mice were injected with each at the maximum tolerated dose and, at various times later, blood samples were taken, cells and platelets removed by centrifugation, and serotonin and 5-HIAA concentrations were measured by high performance liquid chromatography. FAA and DMXAA induced six- and sevenfold increases in serotonin and 5-HIAA, respectively, with maximal levels 4 h after drug administration. 8-Methylxanthenone-4-acetic acid, an inactive analogue of DMXAA, failed to increase serotonin and caused only a small increase in 5-HIAA. Endotoxin, vinblastine, and colchicine each caused increases in serotonin and 5-HIAA between 2 and 6 h after drug administration. The mitotic poison paclitaxel, despite inducing growth delays of Colon 38 tumors, did not induce tumor necrosis and caused no increase in serotonin or 5-HIAA up to 6 h. The effect of the presence of subcutaneous Colon 38 tumors was tested and found not to affect the induction of increases in serotonin and 5-HIAA by DMXAA and colchicine. We suggest that the increases in plasma serotonin and its metabolite are a result of drug-induced vascular effects in host tissues, and that measurement of these compounds provides a potential means of monitoring drugs exerting vascular effects.

Animals↗
PubMed1997

[Medicated stainless steel ring-165, medicated gamma-intrauterine devices and TCu220C: a multicenter comparative study].

OBJECTIVE: A five-year multicenter comparative study was conducted to observe the clinical efficacy, side effects, and menstrual blood loss (MBL) of medicated stainless steel ring 165 (MSSR-165), medicated gamma-Intrauterine devices (gamma-IUD) (both containing indomethacin and copper) and TCu220C for exploring new kinds of IUD to reduce MBL after IUD insertion. METHODS: MSSR-165 and medicated gamma-IUD, with TCu220C as a control, were randomly inserted (one thousand in each group) in women 12 hospitals nation wide in October 1988. Follow-ups were performed at the time of 3, 6, 12, 24, 36, 48 and 60 months after IUD insertion. The efficacy of the IUDs was calculated with life table method. A quantitative comparison of MBL was made before and 3, 6, 12, 24, 36 and 60 months after the IUD insertion in 20 volunteers. RESULTS: At the end of 5 years, the pregnancy rates of MSSR-165, medicated gamma-IUD and TCu220C were 3.2, 2.7 and 3.2. The expulsion rates were 7.7, 2.3 and 2.4, while the removal rates for medical reasons were 5.0, 3.8 and 6.4. The cumulative continuation rates were 79.8, 88.7 and 84.9 per 100 women respectively. The average total bleeding time in the first year of MSSR-165 was 22 days, the shortest one among the three IUDs. The quantitative comparison of MBL showed that the gamma-IUD reduced the MBL and the TCu220C increased the MBL apparently. CONCLUSION: With good clinical efficacy, short menstrual bleeding time, as well as the same appearance and insertion technic as stainless steel ring, the MSSR-165 will be easily accepted at the grass root level. The gamma-IUD had good clinical efficacy and higher continuation rate, whereas the side effect of bleeding was not obvious. Both medicated SSR165 and gamma-IUD could be recommended for promotion.

Adult↗
PubMed1997

[Comparison of two techniques used in immediate postplacental insertion of TCu 380A intrauterine device: 12 month follow-up of 910 cases].

OBJECTIVE: To compare the efficacy of hand-insertion and ring forceps-insertion of TCu 380A intrauterine device (IUD) in immediate postplacental insertion (IPPI). METHODS: 910 vaginal delivery women in Shanghai received a TCu 380A IUD inserted within 10 minutes after delivery of the placenta. Among them, 97.7% were primipara. The women were randomly divided into two groups: 470 cases in hand-insertion group and 440 in ring forceps-insertion group. Using life-tale method and X2 test, we compared the expulsion rates and other causes of removal after follow-up for 12 months in the two groups. RESULTS: The follow-up rate at 6 and 12 months were 95.16% and 92.64%, respectively. No uterine perforation and infection occurred in the 910 cases, and only one pregnancy in the hand-insertion group. Expulsions were the main reason for discontinuation. The 12-month gross cumulative expulsion rates were 15.86 and 15.88 per 100 women in the hand-insertion group and ring forceps-insertion group, respectively, and the removal rates due to bleeding and (or) pain were 2.11 and 1.57, respectively. No difference was statistically significant (P > 0.05). CONCLUSION: The two different insertion techniques do not significantly affect discontinuation rates in vaginal IPPI using the TCu 38)A IUD; the TCu 380A IUD appears to be suitable for postpartum insertion in Chinese women.

Adult↗
PubMed1996

Multiple and tissue-specific promoter control of gonadal and non-gonadal prolactin receptor gene expression.

Prolactin receptors (PRLRs) are widely expressed, and multiple mRNA transcripts encoding PRLRs are present in prolactin target tissues. The molecular basis for the control of the PRLR gene expression is currently unknown. Analyses of the 5'-untranslated regions of PRLR mRNAs expressed in gonadal and non-gonadal tissues and their genomic organization revealed three alternative first exons designated as E11, E12, and E13. Each of these exons is alternatively spliced to a common noncoding exon (exon 2, nucleotides -115 to -56) that precedes the third exon containing the translation initiation codon. Alternative utilization of exons E11, E12, and E13, as well as alternative splicing of exon 2, generates multiple 5'-untranslated regions in PRLR transcripts. These alternative first exons (E11, E12, and E13) were found to be utilized in a tissue-specific manner in vivo. E11 is predominantly expressed in the ovary, E12 is specifically expressed in the liver, and E13 is expressed as a predominant form in the Leydig cell and as a minor form in the ovary and liver. Genomic 5'-flanking regions containing the three putative PRLR gene promoters (PI, PII, and PIII) that initiate the transcription of E11, E12, and E13, respectively, were identified. E11 was found to initiate from a single site at -549, E12 from multiple sites at -405, -461, and -506, and E13 from two major sites at -340 and -351. These findings indicate that multiple promoters control transcription of the PRLR gene and provide a molecular basis for the differential regulation of PRLR expression in diverse tissues.

Alternative Splicing↗
PubMed1996

Inflammatory linear verrucose epidermal nevus coexisting with lichen amyloidosus.

The clinical and histopathological findings in a case of inflammatory linear verrucose epidermal nevus coexisting with lichen amyloidosus are presented. A 33-year-old woman had had linear verrucose lesions which were histopathologically compatible with ILVEN, and with which no amyloid deposits were associated, on her left lower leg for 30 years. She had noticed keratotic papules around the verrucose lesions on the left leg for the last 3 years. Histopathology of these papules revealed amyloid deposits in the upper dermis under the hyperkeratotic and acanthotic epidermis. Topical application of DMSO liniment with dexamethasone successfully treated the ILVEN. This remission of both lesions and itching also alleviated the keratotic papules on the left leg.

Administration, Topical↗
PubMed1995

Experimental solid tumour activity of N-[2-(dimethylamino)ethyl]-acridine-4-carboxamide.

N-[2-(Dimethylamino)ethyl]acridine-4-carboxamide (DACA), a DNA intercalator that exerts its antitumour action through the enzyme topoisomerase II, has previously been shown to be curative against the transplantable Lewis lung adenocarcinoma growing as lung tumour nodules in mice. On the basis of this finding as well as its high in vitro activity against multidrug-resistant cell lines, DACA has been chosen for clinical trial under the auspices of the Cancer Research Campaign, United Kingdom. In the present study the activity of DACA was assessed against advanced (5-mm diameter) s.c. colon 38 adenocarcinomas in BDF1 mice using tumour-growth delay as an end point. Its activity was found to be related positively to the total dose given and negatively to the total duration of the dose schedule. Adoption of a split-dose i.p. administration schedule or slow i.v. infusion allowed the administration of large doses without toxicity. The activity of DACA was comparable with that of 5-fluorouracil and superior to that of doxorubicin, cyclophosphamide and the experimental amsacrine analogue CI-921. Mitoxantrone, amsacrine, etoposide, teniposide and daunorubicin showed minimal activity. DACA also demonstrated significant activity against the NZM3 melanoma human cell line growing as a xenograft in athymic mice.

Acridines↗
PubMed1994

Sequence of the 3'-noncoding region of the luteinizing hormone receptor gene and identification of two polyadenylation domains that generate the major mRNA forms.

We present 6.2 kb of the 3'-noncoding region sequence of the rat luteinizing hormone receptor (LHR) gene and identification of two functional polyadenylation (pA) domains, H1 (nt 2368-2491) and H2 (nt 5579-5768) responsible for 3'-end processing of the 2.6/2.3 kb and the 5.8 kb LHR mRNA, respectively. Two identical copies of pA elements AAUAUA in H1 and of AAUAAA in H2 account for micro-heterogeneous poly(A) addition at each of the two pA regions. Both LH holoreceptor and major splice variant form B (lacking the first 266 bp of exon 11) are identified in H1-terminated (2.6 kb and 2.3 kb) and H2-terminated (5.8 kb) mRNA transcripts. A rodent repetitive DNA LINE R domain 3' of H1 within the major 5.8 kb species and a B2 element downstream of H2 were identified. Alignment of the 3'-noncoding region of LHR with TSH, FSH and beta 2-adrenergic receptors indicate that H1 pA signal is unique to the LHR and may represent an insertion domain.

Alternative Splicing↗
PubMed1994

Interaction between endotoxin and the antitumour agent 5,6-dimethylxanthenone-4-acetic acid in the induction of tumour necrosis factor and haemorrhagic necrosis of colon 38 tumours.

The investigational antitumour agent 5,6-dimethyl-xanthenone-4-acetic acid (5,6-MeXAA) induced dose-dependent haemorrhagic necrosis of colon 38 tumours to a similar extent to that induced using bacterial lipopolysaccharide (LPS). TNF-alpha activity in serum and mRNA for TNF-alpha in splenocytes were induced over a broad range of LPS doses, whereas with 5,6-MeXAA, induction occurred only at concentrations approaching the maximum tolerated dose. At concentrations that provided similar degrees of haemorrhagic necrosis, the levels of serum TNF-alpha induced using 5,6-MeXAA were 100-fold lower than those obtained with LPS, indicating that haemorrhagic necrosis was not directly correlated with TNF-alpha levels. There was also no correlation between the degree of tumour necrosis and the duration of growth delay. Treatment with LPS did not induce a significant delay in growth, despite extensive tumour haemorrhagic necrosis, whereas with 5,6-MeXAA, treatments that improved the cure rate did not necessarily give longer growth delays. Therapy using a combination of sub-optimal doses of both compounds was synergistic for the induction of serum TNF-alpha and message for TNF-alpha but was not synergistic for antitumour efficacy. Thus, no correlation is evident between cure rates, duration of growth delay, haemorrhagic necrosis and TNF-alpha induction by 5,6-MeXAA or LPS.

Animals↗
PubMed1991

Tumor-dependent increased plasma nitrate concentrations as an indication of the antitumor effect of flavone-8-acetic acid and analogues in mice.

The antitumor agent flavone-8-acetic acid (FAA) is remarkable because it induces hemorrhagic necrosis, altered tumor blood flow, and cytokine synthesis. We show here that FAA and structurally related analogues increase plasma nitrite plus nitrate (NO2-/NO3-) levels in mice. Dose-dependent increases in plasma NO2-/NO3- concentrations, which reached maximum levels at 12 h, were found following administration of FAA. Furthermore, the presence of a palpable s.c. Colon 38 tumor significantly enhanced the response. Tumor-dependent increases were also observed with the active FAA analogues xanthenone-4-acetic acid, 5-methyl XAA, and 5,6-dimethyl XAA, while the inactive analogue 8-methyl XAA failed to increase plasma NO2-/NO3- concentrations substantially above basal levels. Increased plasma NO2-/NO3- levels were also observed in response to endotoxin (100 micrograms/mouse) and to recombinant human tumor necrosis factor alpha (4 to 16 micrograms/mouse). NO2-/NO3- levels may signify nitric oxide production as a result of stimulation of the L-arginine-dependent pathway in activated macrophages. The tumor dependence of the response may reflect the immunological stimulus imposed by tumor implantation. A clear relationship was found between increased plasma NO2-/NO3- levels and tumor growth delays induced by FAA and xanthenone-4-acetic acid analogues. It is suggested that nitric oxide may contribute to tumor cell death by two mechanisms, alteration of blood flow contributing to tumor ischemia and direct tumor cell killing. Plasma NO2-/NO3- concentrations may be a sensitive indication of the antitumor response to this class of compounds.

Adenocarcinoma↗
PubMed1991

Induction of natural killer activity by xanthenone analogues of flavone acetic acid: relation with antitumour activity.

Flavone-8-acetic acid (FAA) induces haemorrhagic necrosis and tumour regression in experimental tumours and induces natural killer (NK) activity. Xanthenone-4-acetic acid (XAA) forms the basis of a series of analogues of FAA which vary in antitumour potency. FAA, XAA and 15 XAA derivatives were tested for their ability to induce either NK activity in mouse spleens or haemorrhagic necrosis in mouse colon 38 tumours. Some derivatives were active in both assays (one at a dose 8-fold lower than that of FAA). When both assays were quantitated, a significant correlation (r = 0.85; P less than 0.001) was found. NK assays could be useful in screening compounds such as FAA and XAA analogues which appear to mediate their antitumour activity by biological response modification. Since tumour necrosis may not be mediated directly by NK cells, FAA and active XAA derivatives may exert pleiotropic effects that include NK induction and tumour necrosis by acting on host cells to release cytokines.

Animals↗
PubMed1991

Inhibition of growth of colon 38 adenocarcinoma by vinblastine and colchicine: evidence for a vascular mechanism.

Vinblastine or colchicine, administered intraperitoneally to B6D2F1 mice with advanced subcutaneous colon 38 tumours, induced substantial tumour growth delays with progressive development of haemorrhagic necrosis beginning within 8 hours of treatment. Two multidrug-resistant P388 leukaemia sublines, refractory to vinblastine and vincristine when grown as intraperitoneal ascites, were sensitive to necrosis induction when grown as subcutaneous tumours. Vascular labelling with two fluorescent markers indicated that vincristine substantially reduced tumour blood flow within 4 hours after treatment. The effects of vinblastine, vincristine and colchicine were similar to those of tumour necrosis factor alpha in that: (a) similar tumour necrosis and blood flow changes were induced, (b) coadministration of the serotonin antagonist cyproheptidine prevented tumour necrosis and (c) plasma nitrate levels were elevated, indicative of the stimulation of oxidation of L-arginine to nitric oxide. The results suggest that vinca alkaloids and colchicine act on solid tumours by host cell-mediated vascular effects as well as by direct tubulin-mediated cytotoxicity.

Adenocarcinoma↗
PubMed1991

Potential antitumor agents. 63. Structure-activity relationships for side-chain analogues of the colon 38 active agent 9-oxo-9H-xanthene-4-acetic acid.

A series of 16 analogues of the solid tumor active compound 9-oxo-9H-xanthene-4-acetic acid (XAA), with variations in the acetic acid side chain, have been prepared and evaluated for their ability to cause early haemorrhagic necrosis of colon 38 tumors in mice. The results extend the previous SAR for this class and confirm the necessity for a carboxylic acid group in a fixed disposition with respect to the xanthenone chromophore. None of the compounds showed superior potency to XAA itself, with virtually all alterations in the nature of the anionic center or its geometry with respect to the chromophore greatly reducing or abolishing activity. However, alpha-methylation of the side chain was permissible, and the two enantiomers of 5-methyl-alpha-methyl-XAA were separated and tested. Both were active, but the S-(+) enantiomer was much more dose-potent than the R-(-) enantiomer, in both the in vivo tumor necrosis assay and an in vitro assay measuring the stimulation of nitric oxide production by macrophages. This suggests that the enantiomers have different intrinsic activities, rather than differing in their vivo metabolism.

Animals↗