[The development of light-curing soft denture liner]

In this study, a visible light-curing soft denture liner was developed, and 6 methacrylate polyurethane elastomer and a diluent were synthesised, their effect on tensile strength, compression set, Shore A hardness, absorption and solubility were also investigated. The results showed that the elastomer made of polyethylene adipate or polybutylene ether glycol possessed the highest tensile strength and hardness, the elastomer made of polypropylene ether glycol showed low tensile strength and low shore A hardness, the elastomer made of hydroxyl-terminated liquid polybutadiene rubber had a moderate tensile strength and hardness.

[Determination of calcium, magnesium and potassium in nurtured cell by AAS with quick-pulsed nebulization technique and NaOH base digestion]

The sample is digested with 6% NaOH solution and an amount of 50 microl is used for protein content analysis by the method of Comassie Brilliant Blue G250, the residual is diluted with equal 0.4% Lathanurm-EDTA solution. Its Calcium magensium and potassium content are determined by AAS. With quick-pulsed nebulization technique. When a self-made micro-sampling device is used, 20microl of sample volume is needed and it is only the 1/10 approximately 1/20 of the sample volume required for conventional determination. Sensitivity, precision and rate of recovery agree well with those using regular wet ashing method.

[Criteria of measuring mdr-1 gene expression level in breast cancer by RT-PCR]

OBJECTIVE

To formulate criteria of judjing multidrug resistance gene(mdr-1 gene) expression level and to provide basis for predicting chemotherapy response and prognosis.

METHODS

Using reverse transcription-polymerase chain reaction (RT-PCR) assay, the expression of mdr-1 gene in 82 breast cancer samples was detected. The data were treated by statistic analysis system (SAS)-singlevariate analysis.

RESULTS

The level of mdr-1 gene expression clearly deviated from normal to right distribution (P < 0.0001), and thus might be divided by quantiles P50(mdr-1/beta 2-MG = 0.2) and P75 (mdr-1/beta 2-MG = 0.6), which were taken as the criteria for comparing 56 patients' chemosensitivity to ADM, VDS, VCR in vitro and 32 relapsed metastatic patients' chemotherapy response in vivo, seperately. When mdr-1/beta 2-MG < 0.2, the ratio of coincidence was lower between expression of mdr-1 and drug resistance in vitro and in vivo; When mdr-1/beta 2-MG > or = 0.2-< 0.6, the ratio of coincidence elevated slightly, but in 30%-50% of the cases drug resistance in vitro and in vivo did not correlate. When mdr-1/beta 2-MG > or = 0.6, the ratio of coincidence elevated significantly. According to the above-mentioned results, criteria of evaluating mdr-1 gene expression level was formulated: the mdr-1/beta 2-MG ratio < 0.2(P50) was considered as negative expression, the ratio > or = 0.2-< 0.6(P75) was weakly positive expression, > or = 0.6 was strongly positive expression.

CONCLUSIONS

The criteria of mdr-1 gene expression may reflect objectively drug resistance in vitro and chemotherapy response in vivo. The method may also be applicable to other tumours.

[A promoter responsible for over-expression of cholera toxin B subunit in cholera toxin A subunit structure gene]

A promoter sequence, which promotes the transcription of cholera toxin B subunit gene, was found in cholera toxin A subunit structure gene. The transcription starts at the adenine Located at +833, that is 456bp upstream to the A of the initiation codon ATG of cholera toxin B gene. Under the control of the promoter, cholera toxin B subunit was over-expressed as high as 200 mg/L at an optimized culture condition. The chloramphenicol acetyl transferase gene and beta-galactosidase could also be efficiently expressed under the direction of the promoter. This promoter may be responsible for the 6 fold and 7 fold higher expression level of cholera toxin B subunit than cholera toxin A subunit in V. cholerae and Escheria coli respectively. The over-expression of CTB may be useful in preparing vaccine against cholera and facilitating the construction of peptide-bearing immunogenic hybrid proteins.

Rapid-processing procedure for heat polymerization of polymethyl methacrylate in a pressure cooker with automatic controls

This study introduces a new rapid-processing procedure for curing polymethyl methacrylate denture base resin in an automatically controlled pressure cooker. The cooker filled with water was inflated with 6 kgf/cm2 air pressure and heated to 120 degrees C (248 degrees F) and maintained for 10 minutes. No significant differences were found between the new pressure cooker method and the conventional method for surface hardness and porosity (p > 0.05). The pressure cooker significantly shortened polymerization time, and the polymerization is controlled automatically.

[Cloning and screening on tumor-related genes inactivated in rat hepatoma cells. II. Reversion of malignant phenotype of hepatoma cells]

A rat normal expressing cDNA library was established and subsequently its whole DNA was transfected into CBRH-7919 rat hepatoma cell cultures. With neomycin selection and morphological distinction, several reversed colonies were isolated and subcloned. All these colonies showed decreased growth rates, reduced capacity for foci formation on soft agar and tumorigenicity in nude mice compared to CBRH-7919. Analysis of rescued plasmid cDNA from these colonies is under way.

Diagnosis of hepatitis C Virus (HCV) infection by antigen-capturing ELISA

BACKGROUND

Hepatitis C virus (HCV) is a major cause of non-A non-B hepatitis. Detection of circulating antibodies against HCV by enzyme-linked immunosorbent assay (ELISA) has provided the main approach for the diagnosis of HCV infection. Most ELISA kits use a mixture of core, NS3, NS4 and NS5 antigen as capture antigens and enzyme-labeled goat anti-human IgG as conjugate.

OBJECTIVES

To establish an ELISA system based on the antigen-capturing principle, using a recombinant chimeric polyprotein containing four HCV antigenic components as antigen.

STUDY DESIGN

HCV antigens were expressed in Escherichia coli as chimeric polyprotein either in inclusion bodies or in soluble form. Protein expressed in inclusion bodies was used as solid-phase antigen, and the antigen expressed in a soluble form was used as enzyme conjugate after being labeled with horseradish peroxidase (HRP).

RESULTS

Genes coding HCV antigens were cloned and sequenced, chimeric polyproteins containing four immunodominant components (core, NS3, NS4 and NS5) were expressed in E. coli both in soluble and in inclusion body form. These two chimeric proteins retained the antigenicity of HCV antigens. Antibody-capturing ELISA using the chimeric antigens showed a sensitivity of 97% (97/100) and a specificity of 98% (97/99) using the reference panel from the National Institute for the Control of Pharmaceutic and Biological Products of China (NICPBC); the same assay showed a sensitivity of 97.9% (48/49) and a specificity of 100% (43/43) using the self-established reference panel. Antigen-capturing ELISA was set up using the antigen labeled with horseradish peroxidase as conjugate, and was shown to be as sensitive as (97.9%) and more specific than (100%) antibody-capturing ELISA using the reference panel in this work. The antigen-capturing ELISA also showed a high accordance (98.9%) with UBI HCV enzyme immunoassay (EIA) 4.0 kits (United Biomedical Inc. USA).

CONCLUSION

Antigen-capturing ELISA provided a convenient, sensitive and more specific approach for the diagnosis of hepatitis C virus infection.

[Detection of expression of multidrug resistance gene in breast cancer by RT-PCR]

Using RT-PCR technique, we established a method for measuring expression of mdr-1 gene in breast cancer and the conditions affecting PCR results. Expression of mdr-1 gene was detected in 74 breast cancer samples. The results showed that 34.3%(12/35) untreated primary lesions and 59.0%(23/39) relapsed metastatic lesions had positive expression of mdr-1 gene (P < 0.05). In 32 patients, the overall correlation of mdr-1 gene expression with clinical drug sensitivity was 78.1%. The results validate that RT-PCR assay is highly sensitive, relatively quantitative and reliable for measuring levels of mdr-1 gene expression in clinical samples.

Immunologic basis of transplant-associated arteriosclerosis

Although immunosuppressive therapy minimizes the risk of graft failure due to acute rejection, transplant-associated arteriosclerosis of the coronary arteries remains a significant obstacle to the long-term survival of heart transplant recipients. The participation of specific inflammatory cell types in the genesis of this lesion was examined in a mouse model in which carotid arteries were transplanted across multiple histocompatibility barriers into seven mutant strains with immunologic defects. An acquired immune response--with the participation of CD4+ (helper) T cells, humoral antibody, and macrophages--was essential to the development of the concentric neointimal proliferation and luminal narrowing characteristic of transplant arteriosclerosis. CD8+ (cytotoxic) T cells and natural killer cells were not involved in the process. Arteries allografted into mice deficient in both T-cell receptors and humoral antibody showed almost no neointimal proliferation, whereas those grafted into mice deficient only in helper T cells, humoral antibody, or macrophages developed small neointimas. These small neointimas and the large neointimas of arteries grafted into control animals contained a similar number of inflammatory cells; however, smooth muscle cell number and collagen deposition were diminished in the small neointimas. Also, the degree of inflammatory reaction in the adventitia did not correlate with the size of the neointima. Thus, the reduction in neointimal size in arteries allografted into mice deficient in helper T cells, humoral antibody, or macrophages may be accounted for by a decrease in smooth muscle cell migration or proliferation.

[An experimental and clinical study on radix Salviae miltiorrhiae in the treatment of hepatocellular Ca2+ overload during hepatic ischemia/reperfusion injury]

In recent years there has been considerable interest concerning the role of hepatocellular Ca2+ overload which probably was a major factor in hepatic ischemia/reperfusion injury. We studied the effect of radix salviae miltiorrhizae (RSM) on cytosolic free calciumion concentration [(Ca2+)i](nM) in isolated hepatocytes in rats and patients with ischemia reperfusion by microflurometry using fluorescent (Ca2+)i indicator Fura-2/AM. Changes of lipid peroxide free radical (ROO.) signal ranges with in the liver tissue by ESR technique and those of hepatocellular ultrastructure by electronmicroscope were also observed. The results showed that RSM reduced levels of (Ca2+)i and ROO. Ymax (mm) ESR signal rangs. RSM had an effect on protecting hepatocytes against ischemia/reperfusion injury as a useful receptor-operated calcium channels (ROC) blocker.

Post-transcriptional stimulation of transforming growth factor beta 1 mRNA by TGF-beta 1 treatment of transformed human osteoblasts

Following exogenous administration of transforming growth factor-beta 1 (TGF-beta 1) polypeptide to the human osteosarcoma cell line TE-85, we observed a 2- to 6-fold stimulation of steady-state TGF-beta 1 mRNA. The stimulation was dose- and time-dependent, as judged from Northern blot hybridization analyses. A 2- to 6-fold increase of the TGF-beta 1 polypeptide was also found in the media of these cells after TGF-beta 1 treatments. The autostimulation of TGF-beta 1 mRNA was nullified by cycloheximide treatment of the cells. The in vitro transcription rates of the TGF-beta 1 gene by isolated nuclei were not altered by TGF-beta 1 treatment. Under conditions of transcriptional inhibition, the stability of TGF-beta 1 mRNA was enhanced nearly two-fold by TGF-beta 1 treatment. Our findings indicate that TGF-beta 1 can stimulate autologous gene expression and subsequent polypeptide translation by a post-transcriptional mechanism requiring protein synthesis in human osteoblast-like cells. The recognized versatility of TGF-beta 1 autostimulation mechanisms (transcriptional and post-transcriptional) in other mesenchymal cells may apply also to skeletal cells, further underscoring the broad and potent activities of this cytokine.

LEW-to-F344 carotid artery allografts: analysis of a rat model of posttransplant vascular injury involving cell-mediated and humoral responses

A key manifestation of chronic rejection is an obliterative arteriosclerosis. Myointimal thickening in the vessel is preceded by an endothelialitis involving accumulation of host mononuclear cells in the perivascular and intimal spaces. We report a paratopic LEW-to-F344 rat carotid artery transplantation model developed to study the cells, cytokines, and inflammatory response associated with this early phase of vascular immune injury. Compared with contralateral control arteries and isografts, LEW-to-F344 carotid allografts develop intimal thickening with mononuclear cell infiltration that persists (days 20, 45, 75, 90, and 120). Allografted vessels had dense collections of intimal and adventitial leukocytes (CD45+) consisting of equal numbers of T cells and macrophages. There were small but variable numbers of intimal smooth muscle cells. Intimal cells showed dense staining for tumor necrosis factor-alpha, interleukin-8, platelet-derived growth factor, iNOS, and ICAM and weaker labeling for interleukin-1 beta and interleukin-6. There was also prominent staining for interleukin-4 and interleukin-7 with no detectable interferon-gamma or interleukin-2 staining and high titer labeling for IgG1 (but not IgG2). The predominance of the T cell infiltrate coupled with interleukin-4 and IgG1 expression in carotid allografts is consistent with a TH2 response. This contrasts with balloon-injured rat carotids, which evoke a macrophage-dependent proliferative response. These findings demonstrate that there are distinct as well as common activation pathways in various forms of vascular injury and the LEW-to-F344 carotid model provides the opportunity to gain insight into molecular mechanisms regulating alloimmune injury in the vessel.

[Secretory immunoglobulin A in human milk and infants' feces at 1-4 months after delivery]

OBJECTIVE

To determine the concentration of secretory immunoglobulin A (SIgA) in human milk at 1, 2, 3 and 4 months after delivery and in infants' feces in the same period and find out the effect of milk on the content of SIgA in infants' intestine.

METHODS

20 women and 12 breast feeding infants and 13 formula feeding infants were studied, and milk and infants' feces were collected at 1, 2, 3 and 4 months after delivery, respectively. The concentrations of SIgA in milk and feces were determined by radioimmunoassay.

RESULTS

No apparent changes in the concentration of SIgA were found in human milk and feces from breast feeding and formula feeding infants at 1-4 months after delivery, but the concentration of fecal SIgA in breast feeding infants was significantly higher than that in the formula feeding infants, during the first 4 months after birth.

CONCLUSIONS

Human milk can provide a large amount of SIgA for infants. We conclude from these data that human milk is beneficial in protecting the immunological function of infants digestive tract.

Nucleotide sequence of maize dwarf mosaic virus capsid protein gene and its expression in Escherichia coli

The 3'-terminal 1,279 nucleotide sequence of maize dwarf mosaic virus (MDMV) genome has been determined. This sequence contains an open reading frame of 1,023 nucleotides and a 3'-non-coding region of 256 nucleotides. The open reading frame includes all of the coding regions for the viral capsid protein (CP) and part of the viral nuclear inclusion protein (NIb). The predicted viral CP consists of 313 amino acid residues with a calculated molecular weight of 35,400. The amino acid sequence of the viral CP derived from MDMV cDNA shows about 47%-54% homology to that of 4 other potyviruses. The viral CP gene was constructed in frame with the lacZ gene in pUC19 plasmid and expressed in E. coli cells. The fusion polypeptide positively reacted in Western blot with an antiserum prepared against the native viral CP.

Chinese character operating system of traditional Chinese medicine and pharmacology (TCMP)

With the development in research, teaching and literature work in traditional Chinese medicine and pharmacology (TCMP) by means of computers, it has been found that the existing Chinese character operative systems cannot meet the need of carrying out information processing and software development in this field, since these systems do not include many of the common and special terms in TCMP. This makes it inconvenient to exchange academic thoughts in information processing in this field with our colleagues at home and abroad and greatly affects the sharing of the literature data in TCMP. It is therefore necessary to develop a Chinese character operating system applicable to the use of computers in the research of TCMP. Recently, we have developed jointly a Chinese character operating system of TCMP. This system is based on the original GB2312-80 Chinese character international code, to which are added 1,150 Chinese characters commonly used in TCMP. The five-stroke code, which make input possible according to word forms, are used for the input of expanded words. Besides, the system also provides the codes of a number of common names of Chinese materia medica, acupoint names, common terms in traditional Chinese medicine (TCM), TCM disease names, names of classic TCM works, etc. It also provides a convenient character-creating software. We hope that our work will lead to discussions concerning the difficult problems in computer processing of TCMP literature, i.e. the Chinese character.

K-ras mutation in colorectal carcinomas from singapore

54 sporadic colorectal cancers were analyzed for aberrations in the K-ras oncogene. DNA was extracted from frozen tissues obtained from surgical resection and analyzed for mutations in codons 12, 13 and 61 of the K-ras oncogene using single strand conformation polymorphism analysis (SSCP) and direct sequencing. Point mutations in the K-ras oncogene were found in 26/54 (48%) cases, all of which resulted in amino acid substitutions. No other types of mutations (e.g. insertions or deletions) were found. 4 of the mutations were at codon 12, 22 in codon 13 and only 1 was a codon 61 mutant. G-->A transitions were found to be predominant. A remarkable finding was the high preponderance of (13)Gly-(13)Ser mutations (54%). No correlation was observed between K-ras mutations and tumor location, Dukes' stage, differentiation levels, age or sex of the patient.

[Cloning and screening on tumor-related genes inactivated in rat hepatoma cells]

The paper describes an experiment screening tumor-related genes which specifically expressed in rat normal liver cells but inactivated in hepatoma cells with subtractive hybridization technique. During the test, subtracting normal liver cDNA with hepatoma mRNA produces probe-A whereas subtracting hepatoma cDNA by normal liver mRNA gives probe-B. The paper shows six cDNA fragments (TR 1-6) which hybridize probe-A preferentially obtained through dot-blot screening of 2500 colonies with the two probes. Among TR 1-6, special expressions of TR 2 and TR 4 in normal liver cells are further analyzed.

Resistance of human immunodeficiency virus type 1 to acyclic 6-phenylselenenyl- and 6-phenylthiopyrimidines

Acyclic 6-phenylselenenyl- and 6-phenylthiopyrimidine derivatives are potent and specific inhibitors of human immunodeficiency virus type 1 (HIV-1). The development of in vitro resistance to two derivatives, 5-ethyl-1-(ethoxymethyl)-(6-phenylthio)-uracil (E-EPU), was evaluated by serial passage of HIV-1 in increasing concentrations of inhibitor. HIV-1 variants exhibiting > 500-fold resistance to E-EPSeU and E-EPU were isolated after sequential passage in 1, 5, and 10 microM inhibitor. The resistant variants exhibited coresistance to related acyclic 6-substituted pyrimidines and the HIV-1-specific inhibitors (+)-(5S)-4,5,6,7-tetrahydro-5- pyrimidines and the HIV-1-specific inhibitors (+)-(5S)-4,5,6,7-tetrahydro-5- methyl-6-(3-methyl-2-butenyl)imidazo[4,5,1-jk]benzodiazepin-2(1H)- thione (TIBO R82150) and nevirapine, but remained susceptible to 3'-azido-3'-deoxythymidine, 2',3'-dideoxycytidine, 2',3'-dideoxyinosine, and phosphonoformic acid. DNA sequence analysis of reverse transcriptase (RT) derived from E-EPSeU-resistant virus identified a Tyr (TAT)-to-Cys (TGT) mutation at either codon 188 (Cys-188; 9 of 15 clones) or codon 181 (Cys-181; 5 of 15 clones). The same amino acid changes were found in RT from E-EPU-resistant virus, but the Cys-181 mutation was more common (9 of 10 clones) than the Cys-188 mutation (1 of 10 clones). Site-specific mutagenesis and production of mutant recombinant viruses demonstrated that both the Cys-181 and Cys-188 mutations cause resistance to E-EPSeU and E-EPU. Of the two mutations, the Cys-188 substitution produced greater E-EPSeU and E-EPU resistance. The predominance of the Cys-188 mutation in E-EPSeU-resistant variants has not been noted for other classes of HIV-1 specific RT inhibitors. HIV-1 resistance is likely to limit the therapeutic efficacy of acyclic 6-substituted pyrimidines if they are used as monotherapy.

Murine model of accelerated transplant arteriosclerosis

To define the role of specific gene deletions and mutations in the development of transplant arteriosclerosis, we generated an accelerated model of the disease in mice. Carotid arteries were transplanted between B.10A(2R) (H-2h2) donor mice and C57BL/6J (H-2b) recipients and compared with arteries isografted between H-2b mice. Immunosuppressive drugs were not used. Within 7 days, the allografted carotid artery formed a neointima composed of mononuclear leukocytes (CD45+) that were predominantly monocytes or macrophages (ie, CD11b+ cells with single-lobed nuclei). CD4+ and CD8+ cells were present as well. By 30 days, the neointima became exuberant, and mononuclear leukocytes were largely replaced by smooth muscle cells. Cells staining for proliferating-cell nuclear antigen were abundantly present in the intima at both early and late time points, indicating the proliferation of mononuclear leukocytes and smooth muscle cells. The area of the intima increased from day 7 to day 30 (P < .0005), as did the number of nuclei (P = .0005), but the density of the nuclei decreased (P = .02), suggesting the formation of extracellular matrix. Six of the eight isografts formed no neointima, and in samples from the remaining two, a single layer of smooth muscle neointimal cells covered just a portion of the vessel circumference. This model, which reproduces many of the features of human transplant arteriosclerosis but at an accelerated pace, should prove useful for determining the roles in transplant arteriosclerosis of genes that code for components of immunologic and inflammatory responses.

Intracavity frequency doubling in a Ti:sapphire laser: generation of 14-fs pulses at 416 nm

We demonstrate the use of intracavity frequency doubling in a self-mode-locked Ti:sapphire laser to generate pulses as short as 14 fs. We use a 100-microm-thick lithium triborate (LiB(3)O(5)) crystal in a standard Ti:sapphire laser cavity for the frequency doubling. The average blue output power is 30 mW in each of two beams directly from the laser and 11 mW after compression. The repetition rate is 91 MHz, and the spectral bandwidth is a near-transform-limited 19.2 nm centered at 416 nm. To our knowledge, these results represent the shortest pulse duration yet demonstrated in the blue region of the spectrum.

Regeneration of HoxD expression domains during pattern regulation in chick wing buds

The expression domains of genes located at the 5' end of the HoxD (formerly Hox-4) complex appear to correlate with pattern along both the proximal-distal (PrDi) and the anterior-posterior (AP) axes of the developing limb bud, and it has been suggested that the HoxD gene products are involved in the specification of positional information during limb development. The apical ectodermal ridge is required for limb outgrowth and is thought to influence mesodermal cells at the distal end of the limb bud in a region within which patterning events occur. In this paper, we examine the expression of 5' HoxD genes during PrDi pattern regulation in chick wing buds. In limbs undergoing pattern regulation, we demonstrate that the domains of HoxD11 and HoxD13 gene expression are "regenerated" within 24 hr of removal of the distal mesenchyme. In contrast, in limbs which will not form distal structures, HoxD13 expression becomes reduced.

[The upstream sequence of cholera toxin B subunit gene: effect on CTB expression]

In this work, we have studied the effect of cholera toxin A structure gene on the expression of the distal ctxB gene by the methods of deletion and frame-shift mutation. The results showed that: The expression level of Plasmid pUC19CTB, which was constructed by cloning the XbaI-EcoRI restriction fragment into pUC19 and ctxA gene was out-frame with lacZ' gene, is about 30 micrograms/ml; If a frame shift mutation was introduced at XbaI site of pUC19CTB so that the cholera toxin A gene was inframe with lacZ' and could be translated, the expression level of ctxB was decreased to 12 micrograms/ml; When A further deletion from XbaI to ClaI of cholera toxin A gene (about 550bp) was made and ctxA was outframe with LacZ', ctxB expression was decreased two fold compared to pUC19CTB; If the ctxA was inframe with LacZ' so ctxA gene could be translated, the expression level of CTB is much lower than the plasmid outframe with lacZ'. These observations could not be explained by the current knowledge about genetical regulation of cholera toxin operon. The promoter we found located in the cholera toxin A subunit gene, which is responsible for the expression of cholera toxin B subunit, may answer the question why the 550bp non-coding sequence could enhance the expression of cholera toxin B subunit.

Combination of intracellular staining of retrogradely labeled neurons and anterograde fluorescent tracing: use of the confocal laser scanning microscope

This report describes a combined retrograde tracing, intracellular injection and anterograde fluorescence labeling method using the application of confocal laser scanning microscopy. By simultaneously viewing the morphology of identified projection neurons and the distribution of anterogradely labeled fibers and terminals, this approach allows accurate characterization of the anatomical relationships between these two elements. To demonstrate this approach, the retrograde tracer Fast Blue was injected into the bed nucleus of stria terminalis (BNST) and the anterograde tracer tetramethylrhodamine-conjugated dextran was injected into the insular cortex in adult rats. After one week survival time, the brains were fixed and sectioned on a vibratome. Individual BNST projecting neurons identified in the amygdaloid complex on 120 microns thick sections were intracellularly injected with Lucifer Yellow under visual control and analyzed with confocal laser scanning microscopy. The results demonstrate that images from very thin optical sections can clearly show potential synaptic contacts between anterograde labeling and intracellularly labeled projecting neurons. Stacked images from optical sections show, in very great detail, the morphology of projection neurons in three-dimensions. Compared to other methodological combinations, the present method provides a more simple and efficient means to trace three successive components of a putative neuron chain.

Pore formation and mitogenicity in blood cells by the class 2 protein of Neisseria meningitidis

The class 2 outer membrane protein (MIEP) of Neisseria meningitidis has recently been shown to be mitogenic for lymphocytes (Liu, M.A., Friedman, A., Tai, J., Martinez, D., Deck, R. R., Hawe, L. A., Shieh, J. T.-C., Jenkins, T. D., Donnelly, J. J., and Oliff, A. I. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 4633-4637. In this study, a possible connection between MIEP's mitogenicity and its possible action as a porin was investigated. MIEP, purified from the bacterial outer membrane protein complex under denaturing conditions, caused a modest but specific release of ions (86Rb) from both erythrocytes and lymphocytes, ultimately resulting in cell lysis. The dose-response of MIEP on erythrocyte lysis was qualitatively similar to a known porin (protein I from Neisseria gonorrhoeae) but was much less efficient. Induction or preservation of native structure in MIEP increased pore formation, resulting in levels comparable to that of the protein I porin. These observations suggest that native MIEP, free of the other outer membrane proteins of Neisseria meningitidis, can efficiently form pores in cells, but that denatured MIEP is variably and marginally effective. However, pore formation by MIEP was not related to its mitogenicity in lymphocytes, based on: (i) native MIEP was not mitogenic; (ii) denatured MIEP was highly mitogenic; and (iii) denatured MIEP was mitogenic at concentrations below the threshold level for pore formation. Therefore, mitogenicity is dependent upon MIEP being in a denatured, monomeric state and is masked by native conformation.

Position-specific growth of mouse limb bud cells in vitro

The relationship between cellular position and growth control has been studied in cultures of dissociated fragments of mouse limb bud cells. Using cells derived from various positions along the anterior-posterior axis of the limb bud we have developed culture conditions that optimize growth of positionally isolated cells. Under these conditions limb bud cells display an inherent, position-specific growth response; proliferation of cells derived from anterior and central regions of the limb is enhanced over that of posterior derived cells. Thus, within the total population of limb bud cells the in vitro growth of posterior cells is unique and correlates with the positional activity associated with the zone of polarizing activity. Anterior and posterior cells were cocultured to determine whether interactions between these two groups of positionally distinct cells lead to the stimulation of growth that has been observed in vivo. We observe a slight but consistent position-dependent stimulation of growth that is indicative of a mitogenic signal passing between these positionally disparate cells. Similarities between position-related growth dynamics in vivo and in vitro suggest that positional interactions that are important for limb formation can occur between dissociated cells cultured under standard conditions.

[Various methods of processing pyritum]

Five methods of processing pyritum and the effect of temperature fluctuations on processed products were studied using Fe2+ in the decoction, sulphur in processed products and sulphur separated out of processed products after adding hydrochloric acid as indexes. The results may serve as a reference for further study on pyritum.

Inhibition of DNA synthesis and oncogene expression in tumor cells by the biological factor DIF

A regulatory factor isolated from the maternal part of bovine placentas (decidua inhibitory factor, DIF) inhibits the incorporation of thymidine into the DNA of a variety of animal and human tumors. The degree of inhibition is dependent on the concentration of the factor. Results indicate that signal transduction occurs via a Ca2+ mobilizing pathway after specific binding of the inhibitor to tumor cell surface receptors. On of the main consequences of DIF action is the inhibition of c-fos and c-myc expression and/or degradation.

[Inhibitory effect of yunfujing on vestibular stimulative response in rats and volunteers]

Fifty female rats were used in the experiment. With rotation model, Yunfujing was shown to inhibit nystagmic response of rats. The inhibitory effect was 20-30 times stronger than that of Mihuanjun. In Coriolis test, the tolerance time of vestibular stimulative response was taken as a parameter for judging drug efficacy in 32 male volunteers. Following oral administration of Yunfujing at a dose of 400 mg, the tolerance time of vestibular stimulative response was prolonged significantly from 411.34 to 759.63 s. In the mean time, no changes of blood pressure and pulse were observed in the treated group.

Altered plasma membrane ion permeability in mercury-induced cell injury: studies in hepatocytes of elasmobranch Raja erinacea

The effects of HgCl2, CH3HgCl, p-chloromercuribenzene sulfonate (PCMBS), and CdCl2 on plasma membrane and cell metabolic functions of skate (Raja erinacea) hepatocytes in suspension culture were assessed by measuring (a) the rates of Na+-dependent and -independent L-[14C]alanine uptake, (b) Na+-dependent 86Rb+ uptake, a measure of Na-K-ATPase activity, (c) 86Rb+ efflux, a measure of K+ permeability, (d) the difference between the 3H2O and [14C]inulin distribution spaces, a measure of intracellular water volume, (e) cellular ATP concentrations, and (f) glutathione (GSH) and glutathione disulfide (GSSG) levels. The initial rates of L-alanine and 86Rb+ uptake were inhibited by each of these metals in the following order: HgCl2 greater than CH3HgCl greater than PCMBS greater than CdCl2. Inorganic mercury significantly inhibited the initial rates of Na+-dependent L-alanine and 86Rb uptakes at a concentration of 10 microM, whereas 100 microM produced nearly complete inhibition. These effects were dose-dependent, immediate (observed after less than 5 min of incubation with the metal), and persistent. Mercuric chloride also impaired volume regulatory mechanisms in skate hepatocytes: cells treated with 50 microM HgCl2 swelled slowly over a 60-min interval to volumes nearly double those of control cells. In addition, HgCl2 prevented the normal volume regulatory decrease observed after swelling the hepatocytes in hypotonic media. Mercuric chloride (5-50 microM) produced a rapid initial loss of a large fraction of intracellular 86Rb, followed by a slower rate of release of the remaining isotope. These effects were prevented if GSH was added with, but not following HgCl2. In contrast, dithiothreitol, a more permeable thiol, both prevented and even partially reversed the effects of mercury. Mercuric chloride (10 microM) had no effect on cellular ATP, GSH, or GSSG levels for up to 4 hr incubation. These findings indicate that 86Rb+ (K+) efflux is a sensitive indicator of mercury toxicity, and are consistent with the hypothesis that the plasma membrane is a primary target for mercury's effects. A change in membrane permeability to K+ would dissipate transmembrane electrochemical gradients, and may contribute to the apparent inhibition of transport processes energized by these gradients, such as Na+-alanine cotransport, and volume regulatory mechanisms.