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Biological effects of a novel intestinal peptide--inhibiting enterocytogenin on cultured 3T3 mouse fibroblasts and L5178Y mouse lymphoma cells.

The effects of a new intestinal peptide, inhibiting enterocytogenin (IEG) derived from pig intestinal mucosa were studied in vitro on 3T3 mouse fibroblasts and L5178Y mouse lymphoma cell line. IEG caused considerable growth inhibition together with specific morphological changes, necrotic effects as well as formation of monolayers at the highest concentration applied (1000 micrograms/ml). A biologically active fraction (IEG-BAF) derived by further purification of IEG by gel-filtration, proved to possess most of the described activity. The concentrations of IEG and IEG-BAF inhibiting the growth of L5178Y lymphoma cells by 50% (IC50 values) were calculated to be 759 micrograms/ml and 192 micrograms/ml, respectively. IEG-BAF has a molecular mass of 4450 +/- 180 Da and is most probably a peptidylnucleotidate as revealed by spectral analysis.

3T3 Cells↗

Mouse NGF promoter upstream sequences do not affect gene expression in mouse fibroblasts.

The expression of nerve growth factor (NGF) is tightly controlled in a tissue-specific manner during development and in response to injury. In fibroblasts and in other cell types, expression of NGF is regulated at the transcriptional level. In order to elucidate the mechanism of this regulation, we have undertaken the analysis of the mouse NGF promoter in a mouse fibroblast cell line (LTA), using transient transfection of NGF promoter-human growth hormone (hGH) reporter gene plasmids. We find that sequences between +8bp and +120bp, containing an AP-1 site, confer increased levels of expression from the full length and truncated NGF promoters. When this region is deleted, a significant decrease in expression is observed from both the full length promoter and truncated versions thereof. A gradual increase in expression is observed with successive 5' deletions of both the AP-1 containing and AP-1 deleted promoters; this effect results from the juxtapositioning of adjacent plasmid sequences closer to the transcription initiation site and not from deletion of promoter sequences as was previously reported. When the NGF promoter is analyzed using a luciferase reporter plasmid, these 5' promoter deletions have no significant effect on reporter gene expression in fibroblasts. Thus, sequences downstream of the transcription start site influence NGF promoter activity in fibroblasts, but sequences upstream of the TATA box fail to affect promoter activity in these cells.

Animals↗

Establishment of a SCID mouse model having circulating human red blood cells and a possible growth of Plasmodium falciparum in the mouse.

Our previous study has demonstrated that repeated transfusions of bovine red blood cells (RBCs) into SCID mice resulted in a complete substitution of their circulating RBCs. Identical experiments with human (Hu) RBCs, however, gave rise to a poor RBC-substitution because of the rapid elimination of Hu-RBCs from the circulation of SCID mice. Search for substances to decelerate the Hu-RBC clearance picked up some effective polysaccharides, such as sulfated chitin and mannan, but they were not effective enough to achieve a high level of Hu-RBC-substitution. In the present study, we found that Hu-serum significantly extended the lifetime of Hu-RBC in SCID mice and that repeated transfusions of the mice with Hu-RBCs, in combination with Hu-serum administration, resulted in an almost complete substitution of their circulating RBCs. An Hu-RBC-substituted SCID mouse inoculated with Plasmodium falciparum had a parasitemia persisting for two weeks, indicating a possible growth of this parasite in the mouse. Thus, this report gave the first demonstration of a complete substitution of the circulating RBCs in SCID mice with Hu-RBCs and of a successful P. falciparum infection in the mice.

Animals↗

Comparison of the rate of aminoacylation of tRNA isolated from NMRI mouse liver with tRNA isolated from Krebs II ascites or mouse plasmacytoma cells.

A comparison of the initial rates of aminoacylation of tRNAs isolated from different sources for 17 amino acids was performed. tRNA was isolated from NMRI mouse liver (tRNA L) and from Krebs II ascites tumors (tRNA Asc), and aminoacyl-tRNA synthetases were prepared from the latter cells. The aminoacylation of tRNA Asc was 31-88% slower than the charging of tRNA L. In similar studies, tRNA from a mouse plasmacytoma tumor (tRNA Mt) and from suspension cultured cells of the same cell line (tRNA M) were compared to tRNA L in the aminoacylation reaction catalysed by synthetases isolated from tumor or suspension cultured cells. About half of the tRNAs (Mt or M) for the 17 amino acids tested differed in charging rate when compared to tRNA L, but the differences were not as great as those observed in the experiments where tRNA Asc and tRNA L were compared.

Amino Acyl-tRNA Synthetases↗

Functional difference in monoamine transmitters in the behaviorally abnormal mouse mutant (wriggle mouse sagami).

A mutant mouse (wriggle mouse sagami, WMS) with neurological disorders was found in a colony of the BALB/c strain. The clinical signs included tremor, dystonia and involuntary movements. The concentrations of the neurotransmitter substances, noradrenaline (NA), dopamine (DA), 5-hydroxytryptamine (5-HT) and acetylcholine (ACh), were measured simultaneously with their metabolites in dissected brain regions by high-performance liquid chromatography with electrochemical detection. The turnover of 5-HT was significantly higher in the cerebral cortex, hippocampus, hypothalamus, midbrain and pons-medulla of WMS than of the genetic control, BALB/c. The intrastriatal DA and its metabolites, 3,4-dihydroxyphenylacetic acid and homovanillic acid were increased. However, there was no evidence to suggest an increase in turnover rate of this neurotransmitter. An increase in concentration of and decrease in turnover rate of NA were observed in the cerebellum of this mutant. These findings suggest that multiple disturbance of the neurotransmitter system was largely responsible for the manifestation of the clinical signs of WMS.

Acetylcholine↗

PHrmonal specificity of the melanotropin-sensitive adenylate cyclase of mouse melanoma and effect of cyclic AMP on the tyrosinase activity of mouse melanoma cells, in vitro.

Transplantable mouse melanomas possess a melanotropin-sensitive adenylate cyclase system which is responsive to alpha-melanotropin, beta-melanotropin, adrenocorticotropin (ACTH) and prostaglandin E1. It was found that sensitivity to ACTH was not directed towards the ACTH activity but to the intrinsic melanotropin activity of the ACTH molecule. Therefore, the melanotropin-sensitive adenylate cyclase system is hormonally specific to the intrinsic melanotropin activity of peptide hormones and is unique in the melanoma tissue. The significance of the sensitivity to prostaglandin E1 is obscure at present. The melanotropin-sensitive adenylate cyclase requires the presence of Mg2+ or Mn2+, for its enzymic activity. Ca2+ inhibit the enzyme in the presence of a wide range of concentrations of Mg2+. The enzymic activity is ATP concentration-dependent and the saturation concentration appears to be 1 mM. The enzyme is very labile in the unfractionated tumor homogenates. A washed 11000 X g particulate fraction, representing about 30-60% of the total enzymic activity, was found to be more stable and could be stored at 5 degrees C for 2 h without appreciable loss of the activity. This fraction retained sensitivity to melanotropin, prostaglandin E1 and NaF. About 20% of the activity of the tumor homogenate could not be sedimented by centrifugation at 105000 X g for 60 min. This "soluble" fraction was not responsive to melanotropin, prostaglandin E1 and NaF and might be a degradative product produced by the fractionation. Cyclic AMP and alpha-melanotropin were able to increase the tyrosinase activity of isolated mouse melanoma-cells in vitro under the same conditions.

Adenosine Triphosphate↗

Treatment of mouse L-cells with phorbol myristate acetate induces the secretion of a plasminogen activator inhibitor which binds to human and mouse urokinase and human tissue plasminogen activator.

1. Serum-free conditioned medium from L-cells or L-cells treated with the tumor-promotor phorbol myristate acetate (PMA) was analyzed for plasminogen activator (PA) and plasminogen activator inhibitor (PAI) activity. Conditioned medium from control or PMA-treated cells did not contain detectable PA activity when assayed by SDS-PAGE and zymography. 2. Conditioned medium from PMA-treated cells, but not control cells, contained a PAI of Mr = 40,000 da when assayed by reverse zymography. 3. The L-cell PAI formed SDS-stable complexes with purified human (homo sapiens) urokinase and tissue plasminogen activator, as well as, mouse (Mus musculus) urinary PA. 4. These results indicate that biochemical and immunological differences between human and mouse urokinase and human urokinase and human tissue plasminogen activator do not influence the interaction of the L-cell PAI with these enzymes.

Animals↗

Establishment of epithelial cell strains from normal adult mouse lung resembling a urethane-induced lung adenoma cell strain and a metastasizing mouse lung carcinoma cell line.

Epithelial cell strains, designated NAL, have been established from normal lungs of adult female Balb/c mice. The ultrastructural characteristics, effect of dexamethasone on cellular morphology and proliferation rate, and the cytoskeletal protein pattern of NAL suggests that these cell strains may be related to a urethane-induced mouse lung adenoma cell strain NUL and to a metastasizing mouse lung tumour cell line CMT. NAL exhibited no anchorage-independent growth under normal conditions, however extensive passaging in the presence of 5 X 10(-6)M dexamethasone resulted in a colony forming efficiency in soft agar of 8.4% at passage number 30.

Adenoma↗

Expression of a mouse U1b gene in mouse L cells.

A 6.9-kb DNA fragment containing two mouse U1b genes was introduced by cotransfection with the Herpes simplex virus (HSV) thymidine kinase (TK) gene into tk- mouse L cells. The parent Ltk- cells produce primarily U1a RNA and only small amounts of U1b RNA. However, after introduction of exogenous U1b genes by cotransfection these cells express large amounts of U1b RNA. Subcloned DNA fragments containing a single U1b gene and varying amounts of DNA flanking the 5' -end of the gene were introduced into Ltk- cells. All of the constructs containing 400 bp or more upstream of the U1b gene were efficiently expressed. By comparison, a subclone containing only 150 bp of DNA flanking the 5' -end of the U1b gene was not efficiently expressed. The U1b transcripts synthesized in transfected cells were identified by hybrid selection and by precipitation of ribonucleoproteins (RNP) containing U1 RNA with anti-RNP antibody.

Animals↗

A column-switching high-performance liquid chromatographic assay for a novel cytotoxic thioxanthone derivative (WIN 33377) in mouse plasma with toxicokinetic results from a mouse LD10 study.

WIN 33377 (I) is a member of a novel class of cytotoxic antitumor agents, 4-aminomethyl thioxanthone derivatives. A simple, rapid and reproducible method has been developed for the assay of I in mouse plasma using a high-performance liquid chromatographic method utilizing a column-switching technique. The method involves direct injection of buffered plasma to the extraction column for sample clean-up followed by switching onto an analytical column for analysis with UV detection at 256 nm. The method has demonstrated accuracy and precision over the range 10-2500 ng/ml using a 100-microliters plasma sample with a minimum quantifiable level at 10 ng/ml. Stability of mouse plasma samples was demonstrated after storage for 4 weeks at -15 to -20 degrees C, as was the ability of samples to be accurately quantified after a maximum of three freeze-thaw cycles. Recovery was greater than 87% for the compound and the internal standard. The assay was accurate and reproducible with measured values lying within the limits of defined acceptance criteria. The utility of the method was demonstrated by analyzing plasma samples obtained from mice dosed with I as part of a pre-clinical safety study intended to assist in the design of a pharmacokinetically guided dose escalation strategy.

Animals↗

The gene for the beta-subunit of retinal transducin (Gnb-1) maps to distal mouse chromosome 4, and related sequences map to mouse chromosomes 5 and 8.

The heterotrimeric G protein transducin releases cGMP-phosphodiesterase from inhibition in retinal rod photoreceptor cells when stimulated by light-activated rhodopsin. As a result the level of cGMP goes down, the rod plasma membrane hyperpolarizes, and the release of neurotransmitter is modified. We have used a bovine cDNA for the beta-subunit of transducin (G beta 1) to map its gene Gnb-1 to distal mouse chromosome 4. This cDNA also identified two other homologous sequences in the mouse genome. One of the sequences was on chromosome 5 which we identified as the locus of Gnb-2, a second G protein beta-subunit gene. The other sequence was on chromosome 8 and is either a pseudogene or an as yet undiscovered third G beta-subunit gene, here termed Gnb-3.

Animals↗

A linkage map of mouse chromosome 8: further definition of homologous linkage relationships between mouse chromosome 8 and human chromosomes 8, 16, and 19.

Using an interspecific cross, a mouse chromosome 8 linkage map spanning 72 cM has been defined by the segregation of restriction fragment length variants. Linkage and genetic distance were established for 10 loci by analysis of 114 meiotic events and indicated the following gene order: (centromere)-Insr-3.5 cM-Plat-26.3 cM-Crryps/Mel/Jund-3.5 cM-Junb/Ucp-10.5 cM-Mt-1-27.2 cM-Acta2-0.9 cM-Aprt. These data provide further definition of mouse chromosome 8 linkage relationships and the relationship between segments of this chromosome and human chromosomes 8, 16, and 19.

Animals↗

The study of ultraviolet B-induced apoptosis in cultured mouse keratinocytes and in mouse skin.

The responsibility of ultraviolet B (UVB) radiation for the induction of apoptosis in epidermal cells in vitro and in vivo was examined. Using cultured mouse keratinocytes, PAM212 cells, the morphological development of apoptotic cells (AC) after UVB irradiation was observed, and their DNA status was also examined. In addition, histochemical analysis was performed to establish whether the UVB-mediated sunburn cells (SBC) were AC or not. The cultured cells exposed to UVB showed the morphological characteristics of AC, and the electrophoresis of DNA isolated from these cells showed characteristic fragmentation, i.e. 'DNA ladder'. DNA fragmentation was detectable with UVB doses of more than 50 mJ/cm2, and it appeared 12 h after irradiation, indicating endonuclease-mediated DNA damage. In vivo experimentation using the TdT-mediated dUTP-biotin nick end labeling method (TUNEL) for detection of AC showed scattered positive cells in the basal layer of the UVB-irradiated mouse ear skin. The distributed pattern of the TUNEL-positive cells was similar to that of SBCs. These findings suggest that UVB is a causative factor of apoptosis in the epidermal cells, and that SBC is formed as a result of the apoptosis.

Animals↗

mRNAs for activin receptors II and IIB are expressed in mouse oocytes and in the epiblast of pregastrula and gastrula stage mouse embryos.

Activin is a potent inducer of mesoderm in frog embryos. We showed previously that in the mouse, activin beta A is expressed in the uterine decidua near the embryo before and during the first appearance of mesoderm (E4.5-E6.5). Here, using Northern blotting and in situ hybridization, we show that mouse oocytes, E6.5 and E7.5 embryos, and E6.5 and E7.5 decidua contain mRNAs for both activin receptors type II and IIB. The expression of activin receptor type IIB is particularly strong in embryonic ectoderm apparent at E5.5 and continuing through E8.5. These results support the hypothesis that activin derived from the decidua promotes development of mesoderm in the period E5.5-E6.5.

Activin Receptors↗

Characterization of the mouse HNF-4 gene and its expression during mouse embryogenesis.

Hepatocyte nuclear factor 4 (HNF-4) is a member of the nuclear receptor gene superfamily with unknown ligand. It has been assumed to play an important role in the regulation of gene expression in the liver. Here, we report the cloning and characterization of the mouse HNF-4 gene, as well as its expression during embryogenesis. The HNF-4 protein is encoded by ten exons. The gene structure is unique in the steroid receptor superfamily in that the second zinc finger is encoded by two exons. HNF-4 mRNA is expressed in a limited number of mouse adult tissues: liver, kidney, intestine, stomach and skin. HNF-4 could play an important role in the formation and function of visceral yolk sac and in the development of the liver and kidney since its mRNA, as determined by in situ hybridization, appears upon primary differentiation of these organs. As a first step in the study of the regulatory elements of the HNF-4 gene, we mapped the transcription start site and carried out DNase I hypersensitive site (HS) analysis over a region of approximately 22kb upstream of the gene. The complexity of the HSs suggests that multiple elements might contribute to the transcriptional regulation of the HNF-4 gene.

Aging↗

Radioimmunoscintigraphy using technetium-99m-labeled parental mouse and mouse-human chimeric antibodies to carcinoembryonic antigen in athymic nude mice bearing tumor.

Biodistribution and imaging characteristics of Tc-99m-labeled parental mouse and mouse-human chimeric antibodies to carcinoembryonic antigen (CEA), designated F11-39 and ChF11-39, respectively, were evaluated in athymic nude mice bearing the human CEA-producing gastric carcinoma (MKN-45) xenografts. Group F monoclonal antibodies such as F11-39 and ChF11-39 have been found to recognize the protein epitopes present on the domain B3 of the CEA molecule and to discriminate CEA in tumor tissues from the CEA-related antigens. The Tc-99m labeling was performed by immediately mixing a reduced antibody by 2-mercaptoethanol with Tc-99m pertechnetate in the presence of stannous chloride. The labeling yields of the two antibodies were greater than 95% when estimated using gel chromatography. Although these Tc-99m-labeled antibodies were stable in neutral saline solution, Tc-99m from both labeled antibodies was associated with cysteine solution. Technetium-99m ChF11-39 was more susceptible to transchelation than was Tc-99m F11-39. The immunoreactivity of each Tc-99m-labeled antibody was confirmed using MKN-45 cell-binding assay. Biodistribution studies in tumor-bearing mice were performed at 1 h, 5 h, and 20 h after being given IV injections of 3.7 MBq of either Tc-99m F11-39 or Tc-99m ChF11-39. All tumor-to-organ uptake ratios increased with time for both Tc-99m-labeled antibodies. Imaging results also showed selective and progressive accumulation of both Tc-99m antibodies at the tumor site. Both these Tc-99m-labeled antibodies have proved to be good radiotracers giving satisfactory scintigrams of the CEA-producing tumor.

Animals↗

Hepatocyte nuclear factor-4alpha plays pivotal roles in the regulation of mouse carboxylesterase 2 gene transcription in mouse liver.

The mouse carboxylesterase 2 isozyme, mCES2, is thought to play important roles in lipid metabolism and is expressed in the liver, kidney, and small intestine at high levels. In this study, we examined the molecular mechanisms controlling this tissue-specific expression of mCES2, and demonstrated that hepatocyte nuclear factor-4alpha (HNF-4alpha) could enhance transcription of the mCES2 gene in vitro and in vivo. It was found that effects of HNF-4alpha on the level of mCES2 promoter activity were repressed by small heterodimer partner (SHP) and chenodeoxycholic acid (CDCA) in luciferase assays. Accordingly, mCES2 gene transcription was repressed by CDCA treatment in mouse immortalized hepatocytes. Our results suggested that this repression resulted from the combined effects of both inhibition of HNF-4alpha transactivation ability by SHP and reduction of HNF-4alpha expression level. These findings show that HNF-4alpha plays an important role in the regulation of mCES2 gene transcription.

Animals↗

Age-related impairments in operant DMTP performance in the PS2APP mouse, a transgenic mouse model of Alzheimer's disease.

One of the earliest signs of Alzheimer's disease (AD) is loss of memory for recent events. This deficit in short term memory has been characterised in mild/moderate AD patients as a delay-dependent deficit in a delayed matching to sample (DMTS) task. PS2APP mice co-expressing hPS2mut and hAPPswe exhibit a spatial-temporal elevation in brain amyloid deposition and inflammation associated with temporal cognitive decline. The aim of the current study was to train PS2APP mice (C57BL/6JxDBA/2 mixed background) and appropriate control mice (B6D2F1 background) in a rodent delayed response task, the delayed matching to position (DMTP) task, prior to the onset of plaque formation and subsequently at 2-4 monthly intervals to investigate the effect of aging and increasing plaque load on DMTP performance. At 5 months of age (baseline) DMTP performance was equivalent with both PS2APP and control mice demonstrating a working memory curve across increasing delay intervals of 1-24s. A comparison of PS2APP and control mice across ages revealed a selective age-related, delay-dependent, impairment on choice accuracy in PS2APP mice, consistent with the cognitive decline and temporal amyloidosis previously described for this mouse model. These data are also relevant for other conditional transgenic mouse models which allow time-sensitive induction or inhibition of gene expression such that mice can be trained to perform the task prior to activation or inactivation of the gene and tested thereafter.

Age Factors↗