The tumor suppressor p53 regulates its own transcription

The ability of p53 to suppress transformation correlates with its ability to activate transcription. To identify targets of p53 transactivation, we examined the p53 promoter itself. Northern (RNA) analysis and transient transfection experiments showed that p53 transcriptionally regulated itself. A functionally inactive mutant p53 could not regulate the p53 promoter. Deletion analysis of the p53 promoter delineated sequences between +22 and +67 as being critical for regulation. Electrophoretic mobility shift analysis and methylation interference pinpointed the p53 DNA responsive element. When oligomerized in front of a heterologous minimal promoter, this element was regulated by wild-type p53 and not by mutant p53. Point mutations in the DNA element that eliminated protein-DNA interactions also resulted in a nonresponsive p53 promoter. The DNA element in the p53 promoter responsive to p53 regulation is similar to the p53 consensus sequence. However, we have been unable to detect a direct interaction of p53 with its promoter.

Fibronectin binding site in type I collagen regulates fibronectin fibril formation

Mov13 fibroblasts, which do not express endogenous alpha 1(I) collagen chains due to a retroviral insertion, were used to study the role of type I collagen in the process of fibronectin fibrillogenesis. While Mov13 cells produced a sparse matrix containing short fibronectin fibrils, transfection with a wild type pro alpha 1(I) collagen gene resulted in the production of an extensive matrix containing fibronectin fibrils of normal length. To study the amino acids involved in the fibronectin-collagen interaction, mutations were introduced into the known fibronectin binding region of the pro alpha 1(I) collagen gene. Substitution of Gln and Ala at positions 774 and 777 of the alpha 1(I) chain for Pro resulted in the formation of short fibronectin fibrils similar to what was observed in untransfected Mov13 cells. Type I collagen carrying these substitutions bound weakly to fibronectin-sepharose and could be eluted off with 1 M urea. The effect of this mutation on fibronectin fibrillogenesis could be rescued by adding either type I collagen or a peptide fragment (CB.7) which contained the wild type fibronectin binding region of the alpha 1(I) chain to the cell culture. These results suggest that fibronectin fibrillogenesis in tissue culture is dependent on type I collagen synthesis, and define an important role for the fibronectin binding site in this process.

Mutagenesis of ribosomal protein S8 from Escherichia coli: expression, stability, and RNA-binding properties of S8 mutants

Protein S8, a 129 amino acid component of the Escherichia coli ribosome, plays an essential role in the assembly of the 30S ribosomal subunit and in the translational regulation of the spc operon by virtue of its capacity to bind specifically to rRNA and mRNA. To study structure-function relationships within the protein, we have constructed a vector for its high-level expression in vivo and developed efficient methods for its purification. Under our conditions, S8 accumulates to a level of 35% of the cellular protein and can be prepared at a purity of over 98% using either HPLC or a combination of ion-exchange and gel-filtration chromatography. The unique cysteine residue at position 126 was replaced by alanine or serine by oligonucleotide-directed mutagenesis, and the two mutant proteins, CA126 and CS126, were expressed and isolated. The effects of the mutations on the RNA-binding ability, secondary structure, and stability of S8 were assessed. CD spectra indicated that wild-type S8 and the two mutant proteins have very similar secondary structures at 25 degrees C. In addition, both mutants are metabolically stable in vivo as inferred from pulse-chase labeling and immunoprecipitation experiments. However, while CA126 exhibits the same affinity for RNA and the same susceptibility to urea and thermal denaturation as wild-type S8, CS126 is severely impaired in its ability to interact with RNA and displays a dramatic reduction in conformational stability. Our results suggest that Cys126 is unlikely to play a specific role in RNA recognition but that it is an integral part of the RNA-binding domain of protein S8.

Susceptibility of type I collagen containing mutated alpha 1(1) chains to cleavage by human neutrophil collagenase

Two members of the matrix metalloproteinase family which can cleave native types I, II and III triple helical collagens are collagenases from fibroblasts and neutrophils. These enzymes are the products of different genes which share structural motifs but are only 57% identical. In this study, we determined the site of cleavage in the alpha 1(I) chains and showed that the neutrophil collagenase acted at the same site as the fibroblast collagenase. We also used collagens as substrates which were generated by site-directed mutagenesis of the murine Col1a1 gene and found that the pattern of susceptibility to cleavage by purified neutrophil collagenase was indistinguishable from that previously described for the fibroblast collagenase. Collagens containing substitutions of Pro for Ile-776 (P1) were not cleaved; whereas those containing substitutions of Met for Ile-776 were cleaved. Type I collagen which contained alpha 1(I) chains in which there were double substitutions of Pro for Gln-774 (P2) and Ala-777 (P2') were also not cleaved. These type I collagens contained wild type alpha 2(I) chains as well as mutant alpha 1(I) chains in the mixed helical trimers; the alpha 2(I) chain in the trimers containing the resistant alpha 1(I) chains were also not cleaved by the neutrophil collagenase.

[The role of hemorheologic disturbance in experimental acute pancreatitis]

The role of hemorheologic disturbance in experimental acute pancreatitis was studied in Wistar male rats. It was found that pancreatic duct obstruction with secretin stimulation could induce acute interstitial pancreatitis (AIP), but when high molecular dextran intravenous injection being added, acute necrotizing pancreatitis (ANP) was induced. The authors suggest that the high molecular dextran can increase blood viscosity, aggregation of erythrocytes and decrease erythrocyte deformability, which results in pancreatic microcirculatory disturbances and promotes progressive pancreatic necrosis. Hemorheologic disturbance is one of the key factors in the pathogenesis of ANP.

[Effect of baoyuantang on level of serum lipid peroxide and vitamin E in chronic glomerulonephritis]

Serum lipid peroxide (LPO) and vitamin E (VE) were determined in 18 patients with chronic glomerulonephritis (CGN) before and after treatment with Baoyuantang (BYT). It was found that before treatment the level of serum LPO (4.89 +/- 1.85 mumol/L) was higher, while the content of serum VE (4.27 +/- 1.84 micrograms/ml) was lower than those of normal controls (3.36 +/- 0.59 mumol/L, P < 0.001; 7.03 +/- 0.69 microgram/ml, P < 0.05). After treatment with BYT, the level of LPO lowered to 3.76 +/- 1.49 mumol/L, P < 0.05, as compared with the value before treatment, while the content of VE was increased to 5.33 +/- 2.45 micrograms/ml, but without statistical significance. A negative correlation was found between LPO level and VE content both before and after treatment (r = -0.495,P < 0.05; r = -0.522, P < 0.05). The results indicated chronic deficiency of VE in association with an increase in the level of LPO in the kidney in CGN patients and inhibition of LPO by BYT. After treatment complete remission was observed in 5 cases, basic remission in 3, and partial remission in 7.

[A clinical study of intravenous captopril in heart failure]

A clinical study of intravenous captopril was performed in 10 patients with mild heart failure and 20 with severe heart failure. The results indicated that intravenous captopril may rapidly reduce cardiac preload and afterload, increase cardiac output, inhibit renin system activity and decrease plasma level of catecholamine. A short period of treatment with intravenous captopril may produce a rapid symptomatic improvement in patients with acute or severe heart failure. There was a good tolerance with the therapy.

A histological study of the eye lesions in 12 leprosy patients with tuberculoid lesion in 4 eyes

The histological reactions in 12 eyes of 12 leprosy patients were studied (5 BT, 1 BB, 1 BL and 5 LL). Granuloma lesions composed of epithelioid cells, Langerhans giant cells, macrophages and lymphocytes were found in various intraocular tissues, e.g. cornea, sclera, iris, ciliary body or retina in 4 patients (1 BT and 3 LL). Of the 3 LL patients, according to the records, 2 were cured and in the other patient the outcome of the treatment was not mentioned. In view of the finding of the granulomatous lesions in the clinically cured patients and tuberculoid granuloma in the intraocular tissues in the LL patients, could there be some peculiarities in the intraocular sites? Or perhaps the tuberculoid reaction is just a manifestation of an upgrading reaction? More examinations on human leprosy eye specimens will be needed to answer these questions.

Mainstream and sidestream cigarette smoke-induced DNA adducts in C7Bl and DBA mice

Exposure to environmental tobacco smoke (ETS), which is largely composed of the sidestream cigarette smoke, has been implicated in increased incidence of cancer among nonsmokers. The present study was conducted to compare the potential of mainstream and sidestream cigarette smoke to induce DNA adducts in mice. Groups of female C57Bl and DBA mice were exposed twice daily for 65-70 weeks to mainstream or sidestream smoke from the University of Kentucky reference cigarettes (2R1) in a nose-only exposure system. Animals received a total particulate matter dose of about 16 and 6 mg/kg body weight/exposure and exhibited blood carboxyhemoglobin levels of about 16 and 34%, for mainstream and sidestream smoke-exposed groups, respectively. Pulmonary aryl hydrocarbon hydroxylase (AHH) activity was induced by about 2- to 3-fold in both mainstream and sidestream groups of C57Bl and in mainstream smoke-exposed group of DBA mice, but not in sidestream smoke-exposed DBA mice. An analysis of total DNA adduct levels by the 32P-postlabeling assay showed a significant (12- to 25-fold) increase in the magnitude of preexisting lung DNA adducts in both mainstream and sidestream smoke-exposed C57Bl and DBA mice. Smoke exposures did not affect the total preexisting DNA adducts in liver of either strain. It is concluded that both mainstream and sidestream smoke are capable of enhancing preexisting DNA adducts in the lungs of chronically smoke-exposed mice.

[Effect of different preparations of ginger on blood coagulation time in mice]

The experiments indicate that the decoction, ether extraction and suspension liquid of roasted ginger and charcoal of ginger all can markedly shorten the blood coagulation time in mice, while the decoction, ether extraction of fresh ginger and dry ginger cannot. The decoction of ginger charcoal has stronger effect than roasted ginger in shortening the blood coagulation time in mice. The effect of decoction of ginger charcoal on blood coagulation time tends to increase when the dosage is increased.

Cortactin, an 80/85-kilodalton pp60src substrate, is a filamentous actin-binding protein enriched in the cell cortex

Two related cellular proteins, p80 and p85 (cortactin), become phosphorylated on tyrosine in pp60src-transformed cells and in cells stimulated with certain growth factors. The amino-terminal half of cortactin is comprised of multiple copies of an internal, tandem 37-amino acid repeat. The carboxyl-terminal half contains a distal SH3 domain. We report that cortactin is an F-actin-binding protein. The binding to F-actin is specific and saturable. The amino-terminal repeat region appears to be both necessary and sufficient to mediate actin binding, whereas the SH3 domain had no apparent effect on the actin-binding activity. Cortactin, present in several different cell types, is enriched in cortical structures such as membrane ruffles and lamellipodia. The properties of cortactin indicate that it may be important for microfilament-membrane interactions as well as transducing signals from the cell surface to the cytoskeleton. We suggest the name cortactin, reflecting the cortical subcellular localization and its actin-binding activity.

[Effects of total coumarins, essential oil and water extracts of Cnidium monnieri on plasma prostaglandin and cyclic nucleotide in the rats of kidney-yang insufficiency]

Effects of total coumarins, essential oil and water extracts of Cnidium monnieri on plasma prostaglandin (PGE2 and PGF2 alpha) and cyclic nucleotide levels in rats of Kidney-Yang insufficiency were studied. 55 rats were divided randomly into 5 groups, Group I was administered orally with saline (normal group), group II was injected with intraperitonally hydrocortison acetate to induce Kidney-Yang insufficiency (control group), group III, group IV and group V (experimental groups) were injected with hydrocortison acetate, the same as group II, and administered orally with the total coumarins, essential oil and water extracts of Fructus Cnidii respectively. The levels of plasma PGE2, PG2 alpha and plasma cAMP, cGMP were measured. In group II, in comparing with those of group I, the levels of plasma PGE2, and PGF2 alpha decreased significantly (P < 0.01), and the value of cAMP/cGMP also lowered obviously (P < 0.01) due to the significant reduction of cAMP and insignificant change of cGMP. In group III and group V, the above-mentioned indices changed significantly (P < 0.01 or 0.05) compared with those of group II, and after treatment it normalized basically in comparing with those of group I. In group IV, those indices didn't change regularly and apparently as group III and group V did, compared with group II, and could not normalize satisfactorily. It is suggested that the coumarins in the fruit of Cnidium monnieri are probably the effective ingredients to invigorate Kidney and strengthen Yang, while the efficacy of essential oil remained unconfirmed.

[Formation of mouse chimeras from early embryonic pluripotential stem cell]

Three chimeric mice were produced by injecting the embryonic stem cell-CCE cells into the cavity of 3.5 day host blastocysts from Kunming and C57BL/6J mice. By analyses of glucose phosphate isomerase (GPI-1), the results show a contribution from CCE cells in heart tissue of female Kunming chimera. Breeding experiments demonstrated that all chimeric mice were fertile but none of 3 chimeras produced germ line transmission.

Reaction of 3-Methylenecholest-5-ene With Singlet Oxygen: Peroxyl Radical Cyclization Competitive With Allylic Rearrangement

3-Methylenecholest-5-ene reacts with singlet oxygen to give 5α-hydroperoxy-3-methylenecholest-6-ene which, in turn, rearranges rapidly to 3β-hydroperoxy-5α,3α-( epidioxymethano )cholest-6-ene by free-radical cyclization , and 7α-hydroperoxy-3-methylenecholest-5-ene by allylic rearrangement.

Elevated plasma levels of VWF:Ag in hyperthyroidism are mediated through beta-adrenergic receptors

Thyroid dysfunction influences the levels of Von Willebrand factor (VWF:Ag). Plasma VWF:Ag levels in 35 hyperthyroid patients were significantly elevated, which had a positive correlation with both T3 (Triiodothyronine) and T4 (Thyroxine) levels. A follow-up study of seven hyperthyroid patients undergoing anti-thyroid therapy showed that the elevated VWF:Ag levels returned to normal range with the normalization of thyroid function. On the other hand, after administration of 160 mg/day of propranolol, a specific blocker of beta-adrenergic receptors, to five hyperthyroid patients for twenty-eight days, plasma VWF:Ag levels returned to normal range, while T3, T4 levels remained high without significant alteration. These results demonstrated that the elevation of plasma VWF:Ag by thyroid hormone is mediated through beta-adrenergic receptors, which may be useful to further understand the physiological and pathological roles of thyroid hormone in the regulation of VWF:Ag levels.

Potentiation of cyclic adenosine monophosphate production by thrombin in the human erythroleukemia cell line, HEL

The human erythroleukemia cell line (HEL) has been used as a model system for studying signal transduction processes as they might relate to platelet/megakaryocyte function. We were interested in examining the role of thrombin in the regulation of adenylyl cyclase in this cell line. As opposed to its predominantly inhibitory effects on cyclic AMP production in platelets or in membranes from HEL cells, our initial experiments in intact HEL cells revealed that thrombin markedly potentiated the cyclic AMP response to prostaglandin E1 (2.9 +/- 0.2-fold), prostacyclin (1.9 +/- 0.2-fold) and carbacyclin (2.5 +/- 0.5-fold), measured either by radioimmunoassay or by the [3H]adenine preloading procedure. Thrombin, although ineffective alone, also potentiated cyclic AMP production stimulated by vasoactive intestinal peptide (1.6 +/- 0.2-fold), cholera toxin (3.0 +/- 0.6-fold) and AIF4- (2.3 +/- 0.6-fold), but not by forskolin (0.9 +/- 0.1-fold). The thrombin effect 1) produced an increase in the efficacy of the prostaglandins with no change in potency; 2) was long-lived; 3) required the proteolytic activity of thrombin; 4) was insensitive to pertussis toxin; and 5) was at least partially mimicked by trypsin, extracellular ATP and UTP, platelet activating factor and activators of protein kinase C. Down-regulation of protein kinase C or pre-exposure to the protein kinase inhibitor staurosporine blocked the potentiating effect. Together, these results suggest that in HEL cells, the mechanism of thrombin potentiation of cyclic AMP production may involve alterations in the interaction between stimulatory guanine nucleotide binding protein and the catalytic subunit of adenylyl cyclase, possibly involving protein kinase C-mediated phosphorylation.

An X-linked human collagen transgene escapes X inactivation in a subset of cells

Transgenic mice carrying one complete copy of the human alpha 1(I) collagen gene on the X chromosome (HucII mice) were used to study the effect of X inactivation on transgene expression. By chromosomal in situ hybridization, the transgene was mapped to the D/E region close to the Xce locus, which is the controlling element. Quantitative RNA analyses indicated that transgene expression in homozygous and heterozygous females was about 125% and 62%, respectively, of the level found in hemizygous males. Also, females with Searle's translocation carrying the transgene on the inactive X chromosome (Xi) expressed about 18% transgene RNA when compared to hemizygous males. These results were consistent with the transgene being subject to but partially escaping from X inactivation. Two lines of evidence indicated that the transgene escaped X inactivation or was reactivated in a small subset of cells rather than being expressed at a lower level from the Xi in all cells, (i) None of nine single cell clones carrying the transgene on the Xi transcribed transgene RNA. In these clones the transgene was highly methylated in contrast to clones carrying the transgene on the Xa. (ii) In situ hybridization to RNA of cultured cells revealed that about 3% of uncloned cells with the transgene on the Xi expressed transgene RNA at a level comparable to that on the Xa. Our results indicate that the autosomal human collagen gene integrated on the mouse X chromosome is susceptible to X inactivation. Inactivation is, however, not complete as a subset of cells carrying the transgene on Xi expresses the transgene at a level comparable to that when carried on Xa.

Molecular genetic analysis of bacteriophage P22 gene 3 product, a protein involved in the initiation of headful DNA packaging

Bacteriophage P22 DNA packaging events occur in processive series on concatemeric phage DNA molecules. At the point where such series initiate, the DNA is recognized at a site called pac, and most molecular left ends are generated within six short regions called end sites, which are present in a 120 base-pair region surrounding the pac site. The bacteriophage P22 genes 2 and 3 proteins are required for successful generation of these ends and DNA packaging during progeny virion assembly. Mutants lacking the 162-amino-acid gene 3 protein replicate DNA and assemble functional procapsids. In this report we describe the nucleotide changes and DNA packaging phenotypes of a number of missense mutations of gene 3, which give the phage a higher than normal frequency of generalized transduction. In cells infected by these mutants, more packaging events initiate on the host chromosome than in wild-type infections, so the mutations are thought to affect the specificity of packaging initiation. In addition to having this phenotype, these mutations affect the process of phage DNA packaging in detectable ways. They may: (1) alter the target site specificity for packaging; (2) make target site recognition more promiscuous; (3) affect end site utilization; (4) alter the pac site; and (5) cause apparent random DNA packaging series initiation on phage DNA.

Regulated expression of the human acetylated low density lipoprotein receptor gene and isolation of promoter sequences

The acetylated low density lipoprotein (AcLDL) receptor is expressed on tissue macrophages after their differentiation from monocyte precursors and has been proposed to play a role in the generation of foam cells in atherosclerotic lesions. In the present studies, THP-1 human monocytic leukemia cells were used to investigate mechanisms responsible for expression of the AcLDL receptor gene after treatment with phorbol 12-myristate 13-acetate (TPA). TPA-dependent accumulation of AcLDL receptor mRNA was not detected until after a lag phase of 12 hr and was blocked by concurrent treatment with cycloheximide. In addition, the TPA-dependent induction of AcLDL receptor activity and mRNA levels was inhibited by retinoic acid and dexamethasone treatment. Isolation and sequence analysis of the promoter regions for the human and bovine AcLDL receptor genes indicated high sequence similarity. Binding sites for AP-1 proteins or other known transcription factors were not conserved between the two species, suggesting that novel factors are required for AcLDL receptor expression.

New bone formation in the in vivo implantation of bioceramics. A quantitative analysis

Two kinds of synthetic biomaterial, porous tricalcium phosphate (PTCP) and magnetic porous tricalcium phosphate (MPTCP) ceramic granules were implanted in rat femur. In the period of 4 months, the assessment of serial histological sections, scanning electron microphotographs and quantitative analysis of bone formation in the sections showed that both ceramics are biocompatible and degradable in vivo. More new bone formation occurred in the MPTCP group. Endochondral ossification was seen in both groups. The quantitative analysis in this study is reliable, and may be suitable to the similar experimental models.

[Effect of baoyuantang on erythroid progenitor and clinical observation in chronic renal failure patients]

The erythroid colony formating ability and the therapeutic efficacy were investigated in patients with chronic renal failure (CRF) before and after treatment with baoyuantang. The results showed that the number of CFU-E, BFU-E of bone marrow was found lower in CRF patients than that in normal controls, and there was inhibitory action in the CRF serum on the number of CFU-E, BFU-E of normal human bone marrow. After treatment with baoyuantang, the amount of Hb was increased and creatinine decreased in CRF patients, and its effective rate reached 83.3%. The above-mentioned inhibitory action in CRF serum was also reduced post-treatment. The results indicated that baoyuantang could increase the ability for proliferation and differentiation of erythroid progenitor and adjust anemia in CRF patient.

[Growth regularities of yujin (Curcuma longa L.)]

Based on the characteristics of leaf, root and tuber growth as well as dry matter accumulation, the ontogeny of Yujin is divided into 4 stages. The growth and correlation among the leaf, root and tuber as well as accumulation of essential oils and curcumins have also been studied.