[Immunocytological localization of IAA in the parenchyma cell and vascular elements in the graft union of Cucurbita pepo/Cucurbita moschata at the early developmental stage]

Immuno-gold localization of IAA in cells of the graft union in the explant internode graft of Cucurbita pepo/Cucurbita moschata were investigated with electron microscopy. In parenchyma cells near the graft union, the gold particles were mainly accumulated in nucleus, plastid and endoplasmic reticulum, while no gold particles was detected in Golgi body, mitochondrion, cell wall and vacuoles. In the differentiating xylem element, the gold particles were labeled in secondary wall and cytoplasm. In the sieve element gold particles were found in the sieve plate, sieve pore and cytoplasm. There was a dense label of the gold particles in the companion cell. The role of IAA in the differentiation of the vascular elements was discussed.

[Identification of herba pogostemonis and its confused species Anisomeles indica]

The article reports the morphological, histological and TLC identification for Herba Pogostemonis and its adulterant, Anisomeles indica, which appears recently. It provides foundation for identificating Herba Pogostemonis.

[Polymorphism of 13 STR loci for establishment of Chinese criminal DNA database]

Allele frequency distributions for thirteen STR loci: D3S1358, vWA, FGA, D8S1179, D21S11, D18S51, D5S818, D13S317, D16S539, THO1, TPOX, CSF1PO, and D7S820, have been determined by multiplex amplification and subsequent automatic fluorescent detection. The result of statistical analysis shows that the 13 loci satisfy Hardy-Weinberg expectation. The data obtained from this study will be used as reference data for forensic DNA analysis in China.

Hybrid Rhodospirillum rubrum F(0)F(1) ATP synthases containing spinach chloroplast F(1) beta or alpha and beta subunits reveal the essential role of the alpha subunit in ATP synthesis and tentoxin sensitivity

Trace amounts ( approximately 5%) of the chloroplast alpha subunit were found to be absolutely required for effective restoration of catalytic function to LiCl-treated chromatophores of Rhodospirillum rubrum with the chloroplast beta subunit (Avital, S., and Gromet-Elhanan, Z. (1991) J. Biol. Chem. 266, 7067-7072). To clarify the role of the alpha subunit in the rebinding of beta, restoration of catalytic function, and conferral of sensitivity to the chloroplast-specific inhibitor tentoxin, LiCl-treated chromatophores were analyzed by immunoblotting before and after reconstitution with mixtures of R. rubrum and chloroplast alpha and beta subunits. The treated chromatophores were found to have lost, in addition to most of their beta subunits, approximately a third of the alpha subunits, and restoration of catalytic activity required rebinding of both subunits. The hybrid reconstituted with the R. rubrum alpha and chloroplast beta subunits was active in ATP synthesis as well as hydrolysis, and both activities were completely resistant to tentoxin. In contrast, a hybrid reconstituted with both chloroplast alpha and beta subunits restored only a MgATPase activity, which was fully inhibited by tentoxin. These results indicate that all three copies of the R. rubrum alpha subunit are required for proton-coupled ATP synthesis, whereas for conferral of tentoxin sensitivity at least one copy of the chloroplast alpha subunit is required together with the chloroplast beta subunit. The hybrid system was further used to examine the effects of amino acid substitution at position 83 of the beta subunit on sensitivity to tentoxin.

Seasonal variations in mood and behavior among Chinese medical students

OBJECTIVE

The goal of this study was to estimate the frequency of seasonal variations in mood and behavior among Chinese medical students.

METHOD

A total of 1,358 medical students were surveyed with Chinese versions of the Seasonal Pattern Assessment Questionnaire and the Beck Depression Inventory in Jining, China.

RESULTS

The mean global seasonality score was 8.3 (SD=3.6) out of a possible 24; 81.7% (N=1,110) of the subjects reported some trouble adapting to changing seasons. Summer difficulties were more common than winter difficulties by a ratio of 3:2; estimated rates of summer seasonal affective disorder and subsyndromal seasonal affective disorder were 4.4% and 8.0%, respectively, compared with corresponding winter rates of 2.4% and 5.7%.

CONCLUSIONS

These results suggest that seasonal variations in mood and behavior are common in China. The predominance of summer difficulties stands in contrast to that in most Western studies and is consistent with the only other published study performed in Asia.

Summer and winter patterns of seasonality in Chinese college students: a replication

The goal of this study is to replicate an earlier epidemiological finding of seasonal changes in mood and behavior among Chinese medical students using an independent study population. Three hundred nineteen college students were surveyed with a Chinese version of the Seasonal Pattern Assessment Questionnaire (SPAQ) and the Beck Depression Inventory (BDI) in Jining, China, during March of 1996. The frequency of seasonal patterns and prevalence rates of seasonal affective disorder (SAD) were estimated and compared with data from the medical student survey conducted in the same city. The mean Global Seasonality Score (GSS) of this college student sample was 9.9 +/- 4.9; 84% of the subjects reported some problems with the changing seasons. Summer difficulties were more prevalent than winter difficulties by a ratio of 1.9 to 1 (38.9% v 20.1%). The estimated rates of summer SAD and subsyndromal-SAD (s-SAD) were 7.5% and 11.9%, respectively, as compared with the corresponding winter figures of 5.6% and 6.3%. In addition, the prevalence estimates of winter pattern or winter SADs were higher in males than in females, but the corresponding summer figures showed no gender difference. Compared with the data from the medical student survey, this college student sample had a higher GSS (P < .01) but comparable summer to winter and female to male ratios for the prevalence of SADs (P > .05). These results replicate our previous findings that seasonal problems are common in China, but the predominant problems are summer difficulties rather than winter difficulties, and there is no female preponderance in the prevalence estimates of such problems. Both findings stand in contrast to most Western studies but are consistent with the only other published study performed in the Orient.

[A comparative study of finger plethysmography and aortic pressure for monitoring the effect of external counterpulsation]

Invasive pressure detecting and monitoring of aortic root was conducted in 20 volunteers so as to study the effect of Enhanced External Counterpulsation (EECP) on aortic pressure and finger plethysmography. The results demonstrated that the changes of aortic diastolic pressure linearly related to the counterpusation's bladder pressure, and the aortic augmentation increased to the top of 168.56 mmHg with a D/S ratio of 2.75(amplitude ratio of diastolic waveform and systolic waveform, D/S ratio) following the bladder pressure of 0.45 Kg/cm2. With the increase of bladder pressure, the dp/dt of aortic augmentation elevated gradually, but a down-regulating trend was seen in systolic waveform. During EECP, the starting time of plethysmographic augmentation had a mean delay of 108.20 +/- 25.70 ms comparing with that of aortic augmentation. The duration between the starting time of aortic systolic waveform and that of finger plethysmogram was arround 96.69 +/- 38.70 ms. When the bladder pressure changed, no significant difference was observed among them. The D/S ratio of finger plethysmographic waveform changed in concord with that of aortic pressure with the promotion of bladder pressure. Therefore, a relationship between aortic D/S ratio (Y) and plethysmographic D/S ratio (x) was constructed by the linear regression analysis: Y = 0.376 + 0.457X. It can be concluded that EECP has significant effects on aortic D/S ratio, aortic peak augmentation and its dp/dt value. Finger plethysmography, to date, still plays important roles in monitoring and controlling EECP work safely and effectively.

Recombinant human (rh)IL-4-mediated apoptosis and recombinant human IL-6-mediated protection of recombinant human stem cell factor-dependent human mast cells derived from cord blood mononuclear cell progenitors

Although stem cell factor (SCF) appears to be the major growth factor for human mast cells, other factors undoubtedly play important roles in the development, survival, and function of these cells. The current study examined the effects of recombinant human (rh) IL-4 and rhIL-6 on rhSCF-dependent development and survival of human mast cells derived in vitro from cord blood progenitor cells. After 4-8 wk of culture with rhSCF and various amounts of rhIL-4, a dramatic decline in mast cell numbers was observed with rhIL-4, the EC50 being about 0.1 ng/ml. Numbers of other cell types remained high. Mast cells derived from cord blood progenitors after 7 wk of culture with rhSCF alone displayed an MCT phenotype and expressed Kit, FcepsilonRI, and IL-4R on their surface. Mast cells examined after purification by immunomagnetic sorting became apoptotic within hours after exposure to rhIL-4, a phenomenon blocked by anti-IL-4 Ab. Because rhIL-4-dependent apoptosis but not the loss of mitochondrial membrane potential was prevented by the pan-caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-(Z-VAD)-fluoromethylketone, mitochondrial perturbation most likely preceded caspase activation. Consistent with this conclusion was the observation that both apoptosis and loss of mitochondrial membrane potential (Deltapsim) were inhibited by cyclosporin A in combination with aristolochic acid. rhIL-6 protected cord blood mast cells from rhIL-4-induced apoptosis. Thus, IL-4 can cause both maturation and apoptosis of human mast cells, the latter effect being abrogated by IL-6.

[The effects of sex hormone on blood vessels]

OBJECTIVE

The protective mechanism of sex hormone on blood vessels was investigated to provide evidences for clinical use of hormone replacement therapy in postmenopausal women.

METHODS

To observe the effects of 17 beta-estradiol (E2), progesterone(P), testosterone (T) and E2 combined with P on the relaxation of umbilical arterial rings (UAR) as well as production of nitric oxide (NO) in cultured umbilical endothelial cells(HUVEC) in vitro.

RESULTS

The results showed that 10(-9)-10(-6) mol/L E2 dilation of UAR, but 10(-5) mol/L E2 showed vague effect. P or T had no relaxation effect, but releasing nitric oxide. When in combined trial P at 10(-5) mol/L inhibited the relaxation effect of E2 at 10(-7)-10(-5) mol/L but didn't inhibit E2 10(-9) mol/L. In HUVEC 10(-9)-10(-5) mol/L E2 stimulated the release of nitric oxide when cells incubated for 10 min and 30 min, but did not influence the NO release at 60 min. P and T have different effects on the release of nitric oxide at different concentrations and incubation time. P also inhibited the NO release induced by E2.

CONCLUSIONS

The results indicated that P actually inhibited the relaxation response and induction of NO release by E2, especially at the high concentration. Therefore, we suggested that to use low doses of E2 combined with low dose P for hormone replacement therapy in prevention and treatment of cardiovascular diseases in postmenopausal patient.

Refolding of recombinant alpha and beta subunits of the Rhodospirillum rubrum F(0)F(1) ATP synthase into functional monomers that reconstitute an active alpha(1)beta(1)-dimer

The alpha subunit from the Rhodospirillum rubrum F(0)F(1) ATP synthase (RrF(1)alpha) was over-expressed in unc operon-deleted Escherichia coli strains under various growth conditions only in insoluble inclusion bodies. The functional refolding of urea-solubilized RrF(1)alpha was followed by measuring its ability to stimulate the restoration of ATP synthesis and hydrolysis in beta-less R. rubrum chromatophores reconstituted with pure native or recombinant RrF(1)beta [Nathanson, L. & Gromet-Elhanan, Z. (1998) J. Biol. Chem. 273, 10933-10938]. The refolding efficiency was found to increase with decreasing RrF(1)alpha concentrations and required high concentrations of MgATP, saturating approximately 60% when 50 microgram protein.mL(-1) were refolded in presence of 50 mM MgATP. Size-exclusion HPLC of such refolded RrF(1)alpha revealed a 50-60% decrease in its aggregated form and a parallel appearance of its monomeric peak. RrF(1)beta refolded under identical conditions appeared almost exclusively as a monomer. This procedure enabled the isolation of large amounts of a stable RrF(1)alpha monomer, which stimulated the restoration of ATP synthesis and hydrolysis much more efficiently than the refolded alpha mixture, and bound ATP and ADP in a Mg-dependent manner. Incubation of both RrF(1)alpha and beta monomers, which by themselves had no ATPase activity, resulted in a parallel appearance of activity and assembled alpha(1)beta(1)-dimers, but showed no formation of alpha(3)beta(3)-hexamers. The RrF(1)-alpha(1)beta(1)-ATPase activity was, however, very similar to the activity observed in isolated native chloroplast CF(1)-alpha(3)beta(3), indicating that these dimers contain only the catalytic nucleotide-binding site at their alpha/beta interface. Their inability to associate into an alpha(3)beta(3)-hexamer seems therefore to reflect a much lower stability of the noncatalytic RrF(1) alpha/beta interface.

Induction of AIDS in rhesus monkeys by a recombinant simian immunodeficiency virus expressing nef of human immunodeficiency virus type 1

A nef gene is present in all primate lentiviruses, including human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus of macaque monkeys (SIVmac). However, the nef genes of HIV-1 and SIVmac exhibit minimal sequence identity, and not all properties are shared by the two. Nef sequences of SIVmac239 were replaced by four independent nef alleles of HIV-1 in a context that was optimal for expression. The sources of the HIV-1 nef sequences included NL 4-3, a variant NL 4-3 gene derived from a recombinant-infected rhesus monkey, a patient nef allele, and a nef consensus sequence. Of 16 rhesus monkeys infected with these SHIVnef chimeras, 9 maintained high viral loads for prolonged periods, as observed with the parental SIVmac239, and 6 have died with AIDS 52 to 110 weeks postinfection. Persistent high loads were observed at similar frequencies with the four different SIV recombinants that expressed these independent HIV-1 nef alleles. Infection with other recombinant SHIVnef constructions resulted in sequence changes in infected monkeys that either created an open nef reading frame or optimized the HIV-1 nef translational context. The HIV-1 nef gene was uniformly retained in all SHIVnef-infected monkeys. These results demonstrate that HIV-1 nef can substitute for SIVmac nef in vivo to produce a pathogenic infection. However, the model suffers from an inability to consistently obtain persisting high viral loads in 100% of the infected animals, as is observed with the parental SIVmac239.

An examination of coaxial stacking of helical stems in a pseudoknot motif: the gene 32 messenger RNA pseudoknot of bacteriophage T2

The RNA pseudoknot located at the 5' end of the gene 32 messenger RNA of bacteriophage T2 contains two A-form helical stems connected by two loops, in an H-type pseudoknot topology. A combination of multidimensional NMR methods and isotope labeling were used to investigate the pseudoknot structure, resulting in a more detailed structural model than provided by earlier homonuclear NMR studies. Of particular significance, the interface between the stacked helical stems within the pseudoknot motif is described in detail. The two stems are stacked in a coaxial manner, with an approximately 18 degrees rotation of stem1 relative to stem2 about an axis that is parallel to the helical axis. This rotation serves to relieve what would otherwise be a relatively close phosphate-phosphate contact at the junction of the two stems, while preserving the stabilizing effects of base stacking. The ability of the NMR data to determine pseudoknot bending was critically assessed. The data were found to be a modestly precise indicator of pseudoknot bending, with the angle between the helical axes of stem1 and stem2 being in the range of 15+/-15 degrees. Pseudoknot models with bend angles within this range are equally consistent with the data, since they differ by only small amounts in the relatively short-range interproton distances from which the structure was derived. The gene 32 messenger RNA pseudoknot was compared with other RNA structures with coaxial or near-coaxial stacked helical stems.

[Limbal epithelial autograft transplantation for treatment of pterygium]

OBJECTIVE

To observe the therapeutic effects of limbal epithelial autograft transplantation for treatment of pterygium.

METHODS

Limbal epithelial autograft transplantation was performed on 68 cases (76 eyes) with pterygium or its recurrent lesion. The post-operative follow-up periods ranged from 6 to 18 months (mean, 9.8 months).

RESULTS

Of 68 cases (76 eyes), there were 56 cases (62 eyes) with stable epithelial healing, recovery of corneal transparency and no abnormal proliferation of pterygium-like tissue, and 12 cases (14 eyes) loss of follow-up.

CONCLUSION

To provide new stem cell source for injured limbus with limbal epithelial autograft transplantation is a reasonable therapeutic method for treatment of pterygium.

[Determination of ferulic acid and peoniflorin in siwu decoction prepared by different methods of yellow rice wine]

OBJECTIVE

To compare the influence of different methods with YRW (yellow rice wine) on the composition of Siwu decoction.

METHOD

TCL-SM was used to determine the ferulic acid, paeoniflorin and matters dissolved in ether in Siwu decoction.

RESULT

The Siwu decoction with YRW preparation has the highest contents, while the Siwu decoction containing Chinese Angelica root and Rehmammia root prepared with YRW has the lowest contents.

CONCLUSION

The Siwu decoction prepared with YRW or added with YRW is more helpful for ferulic acid and paeoniflorin to be dissolved out than the Siwu decoction containing Chinese Angelica root and Rehmannia root prepared with YRW.

Efficient ex vivo inhibition of perforin and Fas ligand expression by chimeric tRNA-hammerhead ribozymes

Graft-versus-host disease (GVHD) is a feared complication of allogeneic bone marrow transplantation. Research in rodent models has linked perforin and Fas ligand (FasL), two components of independent lytic pathways, with the induction of GVHD. In this study we characterized two hammerhead ribozymes that cleave their target perforin and Fas ligand RNAs with high efficiency in CTLL-2 cells. The perforin and Fas ligand ribozymes were expressed from a tRNA-directed RNA polymerase III promoter that was inserted in an episomal multicopy plasmid derived from papilloma virus. Chimeric anti-perforin and anti-FasL tRNA-ribozymes had sequences engineered in order to have specific secondary structure effects. These sequence modifications allow the formation of a 5' --> 3' stem structure and also place the ribozyme in a flexible bulge region that keeps the ribozyme separated from the tRNA domain. Northern and RT in situ PCR analyses showed high levels of transcription and efficient transportation to the cytoplasm. The expression of perforin and FasL in CTLL-2 cells was significantly reduced as assessed by RNA and protein analyses.

Characterization of the cutaneous exanthem in macaques infected with a Nef gene variant of SIVmac239

The molecularly cloned viruses known as SIVmac239/R17Y and SIVmac239/YEnef cause extensive lymphocyte activation and induce an acute disease syndrome in macaque monkeys. One manifestation of this syndrome is a severe diffuse cutaneous maculopapular exanthem that is similar to the exanthem associated with HIV-1 infection. To examine the pathogenesis of this exanthem, biopsies obtained throughout the course of clinically evident rash were examined for the presence of virus by in situ hybridization and immunohistochemistry, and the cellular infiltrate was characterized with respect to cellular immunophenotype and chemokine receptor expression. The onset of rash was associated with abundant simian immunodeficiency virus nucleic acid and protein within perivascular dermal infiltrates and occasionally within intraepithelial cells. Analysis of cellular infiltrates showed that biopsies, obtained on the day of rash onset, were composed of equal numbers of CD4+ and CD8+ lymphocytes and abundant alphaEbeta7 positive cells surrounding vessels with upregulated endothelial E-selectin. Moreover, by examining virus expression in sequential skin biopsies from the same animal, the clearance of virus and the resolution of rash were associated with an increase in the percentage of cells expressing CD8, the chemokine receptor CXCR3, and GMP-17, a marker of cytotoxic granules. These results suggest that activated cytotoxic T cells are trafficking to sites of inflammation in the skin and directly or indirectly affect levels of viral replication at these sites.

[Studies on the general properties of a novel microwave plasma enhanced glow discharge source]

This paper introduced a novel microwave plasma enhanced glow descharge source, the structure design and operation were decribed, and the mutual effects of the main characters, such as pressure, current, voltage, microwave power and sputtering rates were also investigated in details.

A mutation in integrase can compensate for mutations in the simian immunodeficiency virus att site

Sequences at the left terminus of U3 in the left long terminal repeat (LTR) and at the right terminus of U5 in the right LTR are important for integration of retroviral DNA. In the infectious pathogenic molecular clone of simian immunodeficiency virus strain mac239 (SIVmac239), 10 of the 12 terminal base pairs form an imperfect inverted repeat structure (5' TGGAAGGGATTT 3' [nucleotides 1 to 12] and 3' ACGATCCCTAAA 5' [nucleotides 10279 to 10268]). Nineteen different mutant forms of SIVmac239 proviral DNA with changes at one or more of the positions in each of the 12-terminal-base-pair regions were constructed. Viral replication was severely or completely compromised with nine of these mutants. Revertants appeared 40 to 50 days after transfection in two independent experiments with mutant 7, which contained changes of AGG to TAC at positions 5 to 7 in U3 and TCC to GAA at positions 10275 to 10273 in U5. Virus produced at these times from mutant 7 transfection replicated upon reinfection with only a slight delay when compared to the wild type. Sequence analysis of the LTR and integrase regions from infected cultures revealed two predominant changes: G to A at position 10275 in U5 and Glu to Lys at position 136 in integrase. Derivatives of clone 7 in which these changes were introduced individually and together were constructed by site-specific mutagenesis. Each change individually restored replication capacity only partially. However, the combination of both mutations restored replicative capacity to that of the original revertants. These results indicate that changes in integrase can compensate for mutations in the terminal nucleotides of the SIV LTR. The results further indicate that resistance to integrase inhibitors may include both integrase and LTR mutations.

[Sequence of HLA-DQA1 promoter region in the Han people]

Polymorphism of HLA-DQA1 promoter region (QAP) in the Han people has been identified. The results revealed a number of differences, some of which are in the critical class II boxes, and generally conserved in HLA-DQA1 promoter region. The major differences occurred in the X box, Y box and S box. Within the X box, the Hans carry a A at position -111, instead of a G, and a G or a A can be present at position -98. Within the S box, the Hans carry a G at position -131. Within the Y box, position -71 is a A rather than a G. Some single base substitutions have been detected from IDDM patients at the 5'-flanking region of the S box and between X box and Y box. Particularly, the insertion of CCA bases has been identified at the position between -157 and -158 in a IDDM patient. These data suggest that the polymorphism of HLA-DQA1 promoter region may play a role in susceptibility to IDDM.

Effect of recombinant human IL-4 on tryptase, chymase, and Fc epsilon receptor type I expression in recombinant human stem cell factor-dependent fetal liver-derived human mast cells

The effect of recombinant human IL-4 (rhIL-4) on the development of recombinant human stem cell factor-dependent fetal liver-derived mast cells was examined. RhIL-4 attenuates the number of mast cells that develop, preferentially affecting the MC(T) type of mast cell. Cellular levels of tryptase and chymase mRNA normalized to that of glyceraldehyde-3-phosphate dehydrogenase were not appreciably affected. Tryptase mRNA levels peaked at least 2 wk before tryptase protein and before chymase mRNA and protein, indicating that tryptase mRNA expression is an early marker of commitment to a mast cell lineage. In contrast, alpha-tryptase and beta-tryptase mRNA levels increased and decreased in parallel. The most dramatic effect of rhIL-4 was to induce expression of functional surface Fc epsilonRI. Expression was maximal by 21 days with 20 ng/ml of rhIL-4 and reached a plateau by 2 ng/ml of rhIL-4 at 4 wk. Fc epsilonRI+ cells increased modestly when myeloma IgE was added to the developing mast cells, but increased synergistically when both myeloma IgE and rhIL-4 were present together. Delayed addition of rhIL-4 progressively diminished Fc epsilonRI expression, as did withdrawal of rhIL-4 during the first 2 wk of culture. RhIL-4 selectively increased Fc epsilonRI alpha mRNA levels at least 10-fold. Mast cells developed in the presence of rhIL-4 released tryptase when exposed to anti-Fc epsilonRI alpha. In conclusion, induction of functional Fc epislonRI on recombinant human stem cell factor-dependent human fetal liver-derived mast cells by rhIL-4 harmonizes with the well-accepted ability of this cytokine to enhance IgE production by B cells.

Effect of recombinant human IL-4 on tryptase, chymase, and Fc epsilon receptor type I expression in recombinant human stem cell factor-dependent fetal liver-derived human mast cells

The effect of recombinant human IL-4 (rhIL-4) on the development of recombinant human stem cell factor-dependent fetal liver-derived mast cells was examined. RhIL-4 attenuates the number of mast cells that develop, preferentially affecting the MC(T) type of mast cell. Cellular levels of tryptase and chymase mRNA normalized to that of glyceraldehyde-3-phosphate dehydrogenase were not appreciably affected. Tryptase mRNA levels peaked at least 2 wk before tryptase protein and before chymase mRNA and protein, indicating that tryptase mRNA expression is an early marker of commitment to a mast cell lineage. In contrast, alpha-tryptase and beta-tryptase mRNA levels increased and decreased in parallel. The most dramatic effect of rhIL-4 was to induce expression of functional surface Fc epsilonRI. Expression was maximal by 21 days with 20 ng/ml of rhIL-4 and reached a plateau by 2 ng/ml of rhIL-4 at 4 wk. Fc epsilonRI+ cells increased modestly when myeloma IgE was added to the developing mast cells, but increased synergistically when both myeloma IgE and rhIL-4 were present together. Delayed addition of rhIL-4 progressively diminished Fc epsilonRI expression, as did withdrawal of rhIL-4 during the first 2 wk of culture. RhIL-4 selectively increased Fc epsilonRI alpha mRNA levels at least 10-fold. Mast cells developed in the presence of rhIL-4 released tryptase when exposed to anti-Fc epsilonRI alpha. In conclusion, induction of functional Fc epislonRI on recombinant human stem cell factor-dependent human fetal liver-derived mast cells by rhIL-4 harmonizes with the well-accepted ability of this cytokine to enhance IgE production by B cells.

[Studies on the spectral characteristics of argon in a novel microwave plasma enhanced glow discharge source]

This paper describes a investigation about the spectral characteristics of argon in a novel microwave plasma enhanced glow discharge source. In different discharge conditions, such as glow discharge, microwave plasma and microwave plasma enhanced glow discharge, there are different distributions of argon spectral lines.

A role for natural simian immunodeficiency virus and human immunodeficiency virus type 1 nef alleles in lymphocyte activation

A T-lymphoid cell line termed 221 was derived from a rhesus monkey infected with herpesvirus saimiri. Growth of 221 cells was dependent on the addition of interleukin-2 (IL-2) to the culture medium. In the absence of IL-2, 221 cells arrested in G0-G1 but did not die. Simian immunodeficiency virus (SIV) replicated efficiently in IL-2-stimulated 221 cells whether or not the nef gene was present. In the absence of IL-2, nef-containing SIV replicated 8 to 100 times more efficiently in 221 cells than did the same virus lacking nef. nef-containing virus preferentially stimulated the production of IL-2 from 221 cells. HIV-1 nef and v-ras genes, but not the c-ras gene, were shown to substitute functionally for SIV nef when tested as recombinant viruses in this assay system. These results demonstrate a role for natural nef in causing lymphoid cell activation, and they provide a system for delineating the biochemical mechanisms responsible for this activation.

Base-pairings within the RNA pseudoknot associated with the simian retrovirus-1 gag-pro frameshift site

Frameshift and readthrough sites within retroviral messenger RNAs are often followed by nucleotide sequences that have the potential to form pseudoknot structures. In the work presented here, NMR methods were used to characterize the base-pairings and structural features of the RNA pseudoknot downstream of the gag-pro frameshift site of simian retrovirus type-1 (SRV-1) and a functional mutant of the SRV-1 pseudoknot. Evidence is presented that these pseudoknots contain two A-form helical stems of six base-pairs each, connected by two loops, in a classic H-type pseudoknot topology. A particularly interesting feature is that the shorter of the two connecting loops, loop 1, consists of only a single adenosine nucleotide that spans the major groove of stem 2. In this respect, the frameshift-associated pseudoknots are structurally similar to the pseudoknot within the gene 32 mRNA of bacteriophage T2, previously characterized by NMR methods. Despite having similar nucleotide sequences, the solvent exchange rates of the imino protons at the junction of the helical stems in the wild-type and mutant frameshifting pseudoknots differ from each other and from the bacteriophage T2 pseudoknot. The implications of this finding are discussed.

Recombinant human granulocyte-macrophage colony-stimulating factor (CSF), but not recombinant human granulocyte CSF, down-regulates the recombinant human stem cell factor-dependent differentiation of human fetal liver-derived mast cells

The effects of recombinant human granulocyte CSF (rhG-CSF) and recombinant human granulocyte-macrophage CSF (rhGM-CSF) on the recombinant human stem cell factor (rhSCF)-dependent development of human mast cells from fetal liver progenitors were examined. Mast cells were identified by immunohistochemical staining for tryptase and by flow cytometric analysis of surface Kit expression. Only rhGM-CSF affected mast cell development. When rhGM-CSF (1, 10, or 100 ng/ml) and rhSCF (50 ng/ml) were added to cell cultures from day 0, both the percentage and absolute numbers of mast cells were diminished after 4 wk compared with cultures exposed to rhSCF alone. Half of the maximal response was achieved at a dose of rhGM-CSF between 0.1 and 1 ng/ml. The Kit+ cells developing in the presence of rhGM-CSF and rhSCF exhibited an intensity of surface Kit expression comparable to that of cells exposed to rhSCF alone. Also, if the initial exposure to rhGM-CSF was delayed for 1 to 3 wk, attenuation of mast cell development waned. These findings are consistent with uncommitted progenitor cells being diverted to nonmast cell lineages by rhGM-CSF, while cells committed to a mast cell lineage, albeit immature, appear to be resistant to the lineage directives of rhGM-CSF. Exposure of fetal liver cells to rhGM-CSF for 1 to 3 days before addition of rhSCF further diminishes the number of mast cells that develop compared with the simultaneous addition of these growth factors on day 0. Whether administration of rhGM-CSF to humans before or together with rhSCF diminishes the mast cell hyperplasia that occurs with rhSCF alone remains to be determined.

Recombinant human granulocyte-macrophage colony-stimulating factor (CSF), but not recombinant human granulocyte CSF, down-regulates the recombinant human stem cell factor-dependent differentiation of human fetal liver-derived mast cells

The effects of recombinant human granulocyte CSF (rhG-CSF) and recombinant human granulocyte-macrophage CSF (rhGM-CSF) on the recombinant human stem cell factor (rhSCF)-dependent development of human mast cells from fetal liver progenitors were examined. Mast cells were identified by immunohistochemical staining for tryptase and by flow cytometric analysis of surface Kit expression. Only rhGM-CSF affected mast cell development. When rhGM-CSF (1, 10, or 100 ng/ml) and rhSCF (50 ng/ml) were added to cell cultures from day 0, both the percentage and absolute numbers of mast cells were diminished after 4 wk compared with cultures exposed to rhSCF alone. Half of the maximal response was achieved at a dose of rhGM-CSF between 0.1 and 1 ng/ml. The Kit+ cells developing in the presence of rhGM-CSF and rhSCF exhibited an intensity of surface Kit expression comparable to that of cells exposed to rhSCF alone. Also, if the initial exposure to rhGM-CSF was delayed for 1 to 3 wk, attenuation of mast cell development waned. These findings are consistent with uncommitted progenitor cells being diverted to nonmast cell lineages by rhGM-CSF, while cells committed to a mast cell lineage, albeit immature, appear to be resistant to the lineage directives of rhGM-CSF. Exposure of fetal liver cells to rhGM-CSF for 1 to 3 days before addition of rhSCF further diminishes the number of mast cells that develop compared with the simultaneous addition of these growth factors on day 0. Whether administration of rhGM-CSF to humans before or together with rhSCF diminishes the mast cell hyperplasia that occurs with rhSCF alone remains to be determined.

An NMR and mutational study of the pseudoknot within the gene 32 mRNA of bacteriophage T2: insights into a family of structurally related RNA pseudoknots

NMR methods were used to investigate a series of mutants of the pseudoknot within the gene 32 messenger RNA of bacteriophage T2, for the purpose of investigating the range of sequences, stem and loop lengths that can form a similar pseudoknot structure. This information is of particular relevance since the T2 pseudoknot has been considered a representative of a large family of RNA pseudoknots related by a common structural motif, previously referred to as 'common pseudoknot motif 1' or CPK1. In the work presented here, a mutated sequence with the potential to form a pseudoknot with a 6 bp stem2 was shown to adopt a pseudoknot structure similar to that of the wild-type sequence. This result is significant in that it demonstrates that pseudoknots with 6 bp in stem2 and a single nucleotide in loop1 are indeed feasible. Mutated sequences with the potential to form pseudoknots with either 5 or 8 bp in stem2 yielded NMR spectra that could not confirm the formation of a pseudoknot structure. Replacing the adenosine nucleotide in loop1 of the wild-type pseudoknot with any one of G, C or U did not significantly alter the pseudoknot structure. Taken together, the results of this study provide support for the existence of a family of similarly structured pseudoknots with two coaxially stacked stems, either 6 or 7 bp in stem2, and a single nucleotide in loop1. This family includes many of the pseudoknots predicted to occur downstream of the frameshift or readthrough sites in a significant number of viral RNAs.

Changes of plasma tPA and PAI activities in patients with diabetic retinopathy

PURPOSE

To investigate the relationship between the diabetic retinopathy (DR) and the activity of plasma tissue plasminogen activator (tPA) and plasminogen activator inhibitor (PAI).

METHODS

tPA and PAI activities were measured by chromatogenous substrate assay in plasma samples obtained from patients with and without diabetic retinopathy (n = 42). Retinopathy was determined by stereoscopic color fundus photographs graded according to a modification of Chinese National Fundus Disease Academic Meeting. And 21 sex-age matched normal people were as controls. This study was in a masked fashion.

RESULTS

1. tPA activity was lower and PAI activity was higher in all of diabetic patients than those in controls (P < 0.001); 2. tPA activity was lower and PAI activity was higher in proliferative DR (PDR) subgroup than those in non-DR (NDR) and background-DR (BDR) subgroups (P < 0.01, respectively); 3. there was no significant difference between BDR and NDR subgroups (P > 0.05); and 4. the results also suggested that the severity of DR and duration of diabetes were correlated negatively with the activity of tPA but positively with that of PAI (r = -0.564, -0.416, 0.671, 0.442; P < 0.01, respectively).

CONCLUSIONS

Reduced plasma tPA activity and enhanced PAI activity in diabetic patients, probably is one of the causes for thromboembolic diseases and are related to the severity of DR and duration of diabetes. Therefore, the change and imbalance between activities of plasma tPA and PAI might play a role in developing and progression of DR.

[Expression of FGF-b and C-myc in rats lung tissue affected by hypoxia]

OBJECTIVE

To study FGF's roles in the reconstruction of vascular walls owing to chronic hypoxia.

METHOD

40 SD rats [corrected] were divided into different hypoxia groups and proceeded with various hypoxic intervals. Expression of FGF-b and transcription of c-myc mRNA of the rats [corrected] lung tissues were detected by immunohistochemical method and in situ hybridization.

RESULTS

FGF-b increased obviously in the smooth muscle and advential tissue of pulmonary arteries after 14 days of hypoxia, whereas C-myc mRNA showed overexpression in rats [corrected] lung tissue from 7th to 21st day of hypoxia.

CONCLUSION

(1) Hypoxia may lead to activation of C-myc oncogene and increase of FGF-b expression in lung tissue. (2) FGF-b and C-myc oncogene takes part in reconstruction of pulmonary arterial wall affected by chronic hypoxia.

In vivo phosphorylation of phosphoenolpyruvate carboxylase in guard cells of Vicia faba L. is enhanced by fusicoccin and suppressed by abscisic acid

Plants regulate water loss and CO2 gain by modulating the aperture sizes of stomata that penetrate the epidermis. Aperture size itself is increased by osmolyte accumulation and consequent turgor increase in the pair of guard cells that flank each stoma. Guard cell phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31), which catalyzes the regulated step leading to malate synthesis, is crucial for charge and pH maintenance during osmolyte accumulation. Regulation of this cytosolic enzyme by effectors is well documented, but additional regulation by posttranslational modification is predicted by the alteration of PEPC kinetics during stomatal opening (FEBS Lett. 352, 45-48). In this study, we have investigated whether this alteration is associated with the phosphorylation status of this enzyme. Using sonicated epidermal peels ("isolated" guard cells) preloaded with 32PO4, we induced stomatal opening and guard cell malate accumulation by incubation with 5 microM fusicoccin (FC). In corroboratory experiments, guard cells were incubated with the FC antagonist, 10 microM abscisic acid (ABA). The phosphorylation status of PEPC was assessed by immunoprecipitation, electrophoresis, immunoblotting, and autoradiography. PEPC was phosphorylated when stomata were stimulated to open, and phosphorylation was lessened by incubation with ABA. Thus, we conclude that regulation of guard cell PEPC in vivo is multifaceted; the effects of regulatory metabolites and the activation status of the enzyme are integrated to control malate synthesis. These results, together with the coincident alteration in the kinetics of the enzyme (FEBS Lett. 352, 45-48), constitute the first unequivocal demonstration of regulatory posttranslational modification of a guard cell protein that is specifically implicated in stomatal movements.

[Stability of jingu tongxial pills]

The stability of Jingu Tongxiao Pills was studied on the basis of accelerated destruction and sample-reserving observation at room temperature. According to the changes of tanshinone IIA in the sample, the time of efficacy determined by the two methods is 1.89 and 2.30 years respectively. Based on the analysis of other indices, the effective period is tentatively determined as two years.

Copper metabolism of holstein and jersey cows and heifers fed diets high in cupric sulfate or copper proteinate

Eight Holstein and 8 Jersey primiparous cows (3 d postcalving) and 8 Holstein and 8 Jersey growing heifers were randomly assigned to 1 of 8 treatments in a 2 x 2 x 2 factorial arrangement to compare Cu metabolism between Holsteins and Jerseys and the bioavailabilities of Cu in Cu proteinate and CuSO4. The variables were Holstein or Jersey, Cu supplementation at 5 or 80 mg/kg of DM, and supplements of CuSO4 or Cu proteinate. Jerseys had higher hepatic Cu concentrations than did Holsteins on d 60 (346 vs. 303 micrograms/g of DM). At the high Cu supplementation, hepatic Cu increased more rapidly, and content was higher in Jerseys than in Holsteins by d 60 (520 vs. 439 micrograms/g of DM). On d 0, plasma Cu concentrations were 0.99 and 0.80 microgram/ml, and, on d 60, concentrations were 0.96 and 0.88 microgram/ml for Jerseys and Holsteins, respectively. Overall, serum ceruloplasmin oxidase activity was greater for Jerseys than for Holsteins. Jersey cows and heifers also had greater hepatic Fe (208 vs. 173 micrograms/g of DM) and lower hepatic Zn (82 vs. 91 micrograms/g of DM) than did Holstein cows and heifers at d 60. The bioavailability of Cu in Cu proteinate and CuSO4 was the same. Plasma Cu concentration and ceruloplasmin have limited value as indicators of Cu status and availability to dairy cows and heifers.

A hammerhead ribozyme that cleaves perforin and fas-ligand RNAs in vitro

Polyfunctional ribozymes targeting more than one RNA might be ideal for treatment of diseases caused by the expression of more than one mRNA. This is the case of Graft versus Host Disease, which in the mouse model is due to the action of two proteins responsible for different lytic pathways: perforin and fasligand. We have created a bifunctional ribozyme fusing two antiperforin and antifas-ligand hammerhead ribozymes with a stretch of CA dinucleotides. This bifunctional ribozyme is able to recognize and cleave in vitro perforin and fas-ligand mRNA in a specific and selective fashion, with a catalytic efficiency similar to that of its individual components.

Utilization of copper in copper proteinate, copper lysine, and cupric sulfate using the rat as an experimental model

One hundred twenty male Sprague-Dawley rats, averaging 108.6 g initial body weight, were used in two feeding experiments to evaluate the utilization of Cu in Cu proteinate, Cu lysine, and cupric sulfate. In Exp. 1, 60 rats were randomly assigned to 12 treatments in a 2 x 2 x 3 factorial arrangement of treatments, with Zn supplementation at 0 or 1000 mg/kg diet, Cu supplementation at 5 or 15 mg/kg diet, and Cu form of CuSO4.5H2O, Cu proteinate, or Cu lysine. The purified basal diet contained .81 mg Cu, 20 mg Zn, and 60 mg Fe/kg diet. Experiment 2 was similar to Exp. 1 except Zn was replaced by Fe. In Exp. 1, feed intake of Cu proteinate (15.74 g/d) and Cu lysine (15.74 g/d) treatments was higher (P < .05) than that of CuSO4 (15.33 g/d). Body weight gain and feed intake were increased by high dietary Cu at either requirement or high levels of dietary Zn (P < .05). There were no differences in feed intake or body weight gain among the treatment groups in Exp. 2 (P > .05). The Cu utilization of Cu proteinate and Cu lysine were higher (P < .05) based on the liver Cu content. The rats fed Cu complexes had a higher liver Fe or Zn content (P < .05) than the rats fed CuSO4, suggesting that Cu complexes are absorbed via another mechanism that differs from that of inorganic Cu and does not interfere with Zn and Fe. Spleen Cu content may be a sensitive indicator of Cu status. High dietary Zn decreased Cu utilization, but this effect was overcome by high dietary Cu.

Induction of lymphocyte proliferation and severe gastrointestinal disease in macaques by a nef gene variant SIVmac239

The molecularly cloned virus known as SIVmac239/YEnef causes extensive lymphocyte activation in unstimulated peripheral mononuclear cell cultures and induces an acute disease syndrome in macaque monkeys. Here we describe the histopathological and immunophenotypic changes and viral localization in peripheral lymph nodes, spleen, and gastrointestinal tract (including the gut-associated lymphoid tissue (GALT) in rhesus monkeys inoculated with SIVmac239/YEnet beginning at day 3 postinoculation (pi). The findings are compared with those of rhesus monkeys inoculated with the same dose of parental SIVmac239. Histopathological examination of peripheral lymphoid tissue and GALT demonstrated marked hyperplasia of T-cell-dependent regions and involution of germinal centers as early as day 7 pi. The most striking lesions were multifocal areas of lymphohistiocytic gastroenteritis and colitis. Cellular infiltrates peaked between day 7 and 14 pi and were composed primarily of CD3+ T lymphocytes and HAM-56+ monocyte/macrophages. Many of these inflammatory cells were also strongly immunoreactive for teh nuclear proliferation antigen Ki-67. Despite the presence of severe gastrointestinal pathology by day 7 pi, no significant difference in the numbers of virus-positive cells in the gastrointestinal tract was observed between these animals and SIVmac239-infected animals examined at the same time point. However, the distribution of virus in the gastrointestinal tract was markedly different, with virus localized to lymphoid nodules of GALT in SIVmac239-infected animals and restricted to areas of lymphohistiocytic gastroenteritis and colitis in animals infected with SIVmac239/YEnef. Our data indicate that the acute disease syndrome induced by SIVmac239/YEnef is not simply related to increased viral replication in the gastrointestinal tract but is likely due to inappropriate virus-induced T lymphocyte activation and proliferation in GALT and subsequent mucosal destruction.

Requirements for lymphocyte activation by unusual strains of simian immunodeficiency virus

When residues 17 and 18 in nef of simian immunodeficiency virus strain SIVmac239 were changed from RQ to YE, the resultant virus was able to replicate in peripheral blood mononuclear cell cultures without prior lymphocyte activation and without the addition of exogenous interleukin-2, caused extensive lymphocyte activation in these cultures, and produced an acute disease in rhesus and pigtail macaques (Z. Du, S. M. Lang, V. G. Sasseville, A. A. Lackner, P. 0. Ilyinskii, M. D. Daniel, J. U. Jung, and R. C. Desrosiers, Cell 82:665-674, 1995). These properties are similar to those of the acutely lethal pathogen SIVpbj14 but dissimilar to those of the parental SIVmac239. We show here that the single change of R to Y at position 17 in nef of SIVmac239 is sufficient to confer the full, unusual phenotype. Conversely, the lymphocyte-activating properties of SIVpbj14 were lost by the single change of Y to R at position 17 of nef. The change of R17F or Q18E in SIVmac239 nef did not confer the unusual in vitro properties. Since SIVpbj14 has a duplication of the NF-kappaB binding sequence in the transcriptional control region, we also constructed and tested strains of SIVmac239/Rl7Y with zero, one, and two NF-kappaB binding elements. We found no difference in the properties of SIVmac239/R17Y, either in cell culture or in vivo, whether zero, one, or two NF-kappaB binding sites were present. Thus, tyrosine at position 17 of nef is absolutely necessary for the unusual phenotype of SIVpbj14 and is sufficient to convert SIVmac239 to a virus with a phenotype like that of SIVpbjl4. Multiple NF-kappaB binding sites are not required for the in vitro properties or for acute disease.

Effect of isothermal radiofrequency radiation on cytolytic T lymphocytes

Previous in vitro studies provide evidence that RF electromagnetic radiation modulates proliferation of human glioma, lymphocytes, and other cell types. The mechanism of RF radiation cell proliferation modulation, as well as mechanisms for effects on other cell physiologic endpoints, are not well understood. To obtain insight regarding interaction mechanisms, we investigated effects of RF radiation exposure on interleukin 2 (IL-2) -dependent proliferation of cytolytic T lymphocytes (CTLL-2). After exposure to RF radiation in the presence or absence of IL-2 cells were cultured at various physiological concentrations of IL-2. Treatment effects on CTLL-2 proliferation were determined by tritiated thymidine incorporation immediately or 24 h after exposure. Exposure to 2450 MHz RIF radiation at specific absorption rates (SARs) of greater than 25 W/kg (induced E-field strength 98.4 V/m) induced a consistent, statistically significant reduction in CTLL-2 proliferation, especially at low IL-2 concentrations. At lower SARs, 2450 MHz exposure increased CTLL-2 proliferation immediately after exposure but reduced 24 h postexposure proliferation. RF radiation effects depended on the mitotic state of the cells at the time of exposure. Comparison of the effects of temperature elevation and RF radiation indicated significant qualitative and quantitative differences.

FTIR studies of recombinant human granulocyte-macrophage colony-stimulating factor in aqueous solutions: secondary structure, disulfide reduction and thermal behavior

Fourier transform infrared spectroscopy (FTIR) has been used to investigate the secondary structure, disulfide reduction and thermal behavior of recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) in aqueous solutions. The contributions of amino-acid side-chain groups to the amide I bands of rhGM-CSF in H2O and in D2O solutions were carefully scrutinized, as 40% of the total 127 amino-acid residues of rhGM-CSF is side-chain absorptive (asparagine, glutamine, etc.). The FTIR results indicated that rhGM-CSF is composed of 46% alpha-helix, 7% beta-sheet, 23% turn and 24% loop/irregular structures which are in good agreement with the X-ray diffractional data. Reduction of rhGM-CSF with dithiothreitol caused apparent unfolding of the native conformation followed by the time-dependent increase of beta-aggregation bands which arose at 1622 and 1693 cm(-1) in H2O, 1613 and 1684 cm(-1) in D2O solutions. The result also showed that tertiary structure can change independently of the secondary structure. Thermal denaturation of rhGM-CSF took place at 55 to 70 degrees C and the denatured protein adopted an irregular structure as revealed by the FTIR spectra. The thermal denaturation did not show the formation of intermolecular beta-aggregates which is typical of most thermal denatured proteins. Moreover, it is partly reversible, indicating a special thermal stability of rhGM-CSF.

Internalization of Kit together with stem cell factor on human fetal liver-derived mast cells: new protein and RNA synthesis are required for reappearance of Kit

Kit, the receptor for stem cell factor (SCF) and the product of the c-kit proto-oncogene, is expressed on fetal liver-derived mast cell progenitors when cultured with SCF. Decreased levels of Kit on the surface of human fetal liver-derived mast cells after exposure to recombinant human SCF were demonstrated by flow cytometry using the YB5.B8 mAb against Kit. Internalization of Kit along with SCF appears to be the principal means by which Kit is lost from the mast cell surface. Neither the beta 3-integrin CD51/CD61 (alpha v beta 3), nor the beta 1-integrins CD49d,e/CD29 (VLA-4 and -5) appeared to be internalized along with Kit-SCF complexes. Reappearance of Kit on day 28 fetal liver-derived mast cells is complete 3 days after exposure of the cells to SCF and is detectable by 2 days. Recovery requires new protein and new RNA synthesis, because Kit did not reappear if cycloheximide or actinomycin D was added to the cells. No substantial change in total Kit mRNA was detected during the resynthesis period, suggesting that post-transcriptional regulation of Kit production is involved. Internalization of Kit in mast cells exposed to soluble SCF may represent a negative regulatory mechanism for this receptor-ligand interaction and down-regulate mast cell properties such as degranulation to SCF.

Internalization of Kit together with stem cell factor on human fetal liver-derived mast cells: new protein and RNA synthesis are required for reappearance of Kit

Kit, the receptor for stem cell factor (SCF) and the product of the c-kit proto-oncogene, is expressed on fetal liver-derived mast cell progenitors when cultured with SCF. Decreased levels of Kit on the surface of human fetal liver-derived mast cells after exposure to recombinant human SCF were demonstrated by flow cytometry using the YB5.B8 mAb against Kit. Internalization of Kit along with SCF appears to be the principal means by which Kit is lost from the mast cell surface. Neither the beta 3-integrin CD51/CD61 (alpha v beta 3), nor the beta 1-integrins CD49d,e/CD29 (VLA-4 and -5) appeared to be internalized along with Kit-SCF complexes. Reappearance of Kit on day 28 fetal liver-derived mast cells is complete 3 days after exposure of the cells to SCF and is detectable by 2 days. Recovery requires new protein and new RNA synthesis, because Kit did not reappear if cycloheximide or actinomycin D was added to the cells. No substantial change in total Kit mRNA was detected during the resynthesis period, suggesting that post-transcriptional regulation of Kit production is involved. Internalization of Kit in mast cells exposed to soluble SCF may represent a negative regulatory mechanism for this receptor-ligand interaction and down-regulate mast cell properties such as degranulation to SCF.

Thermodynamics of folding of the RNA pseudoknot of the T4 gene 32 autoregulatory messenger RNA

Nucleotides U(-67) to C(-40) at the extreme 5' end of the gene 32 mRNA in bacteriophage T4 have been shown to fold into an RNA pseudoknot proposed to be important for translational autoregulation. The thermal denaturation of three in vitro transcribed RNAs corresponding to the pseudoknot region has been investigated as a function of Mg2+ concentration to begin to elucidate the determinants of the structure and stability of this conformation. T4-35 is a 35-nucleotide RNA containing a 5' G followed by the natural T4 sequence starting with the mature 5' end of the mRNA, nucleotides A(-71) to C(-38). A 32-nucleotide RNA, termed T4-32, contains the native sequence form U(-67) to C(40) with 5'GC and 5'CA single-stranded regions appended to the 5' and 3' ends of the core sequence, respectively. T4-28 contains only the 28 core nucleotides, and the predicted closing U(-67)-A(-52) base pair in stem 1 has been replaced with a phylogenetically allowed G(-67)-C(-52) base pair. Ribonuclease mapping of T4-32 and imino proton NMR experiments of T4-35 show that both sequences adopt a pseudoknotted conformation. At pH 6.9 and 50 mM NaCl, T4-35 and T4-32 RNAs are characterized by a single major melting transition over a wide range of [Mg2+] (0-6 mM). The delta H degree of unfolding for T4-35 and T4-32 shows a large dependence on Mg2+ concentration; the maximum delta H degree occurs at about 2.0 mM Mg2+ with further addition of Mg2+ simply increasing the tm. Investigation of the [Mg2+] dependence of the tm suggests that a net of one Mg2+ ion is released upon denaturation of T4-35 and T4-32 RNAs. Over the entire [Mg2+] range, the delta G degree (37 degrees C) for the folding of T4-35 is consistently 1-1.5 kcal mol(-1) more negative than T4-32 due to a higher stabilization enthalpy for the natural sequence molecule. In contrast to this behavior, T4-28 gives consistently higher tm's but less negative enthalpies and is destabilized (at 37 degrees C) by about 0.5-1.5 kcal mol(-1) relative to T4-32 and by about 2-3 kcal mol(-1) relative to T4-35, depending upon cation concentration. (1)H NMR experiments suggest that, even in the presence of 4.0 mM Mg2+, T4-28 RNA does not adopt a stable pseudoknotted conformation. These data show that the stability of the pseudoknot in the gene 32 mRNA encoded by the 28-nucleotide core sequence is significantly influenced by the number and nature of the immediately adjacent "single-stranded" 5' and/or 3' nucleotides appended to the core structure. These findings are discussed within the context of the structural model for the evolutionarily related phage T2 and T6 gene 32 mRNA pseudoknots presented in the following paper [Du, Z., Giedroc, D. P., & Hoffman, D. W. (1996) Biochemistry 35, 4187-4198].

Structure of the autoregulatory pseudoknot within the gene 32 messenger RNA of bacteriophages T2 and T6: a model for a possible family of structurally related RNA pseudoknots

A 36-nucleotide RNA with a sequence corresponding to the 5' end region of the gene 32 mRNA of bacteriophages T2 and T6 was analyzed by one- and two-dimensional NMR methods. NMR results provide clear evidence that the RNA is folded into a pseudoknot structure with two coaxial stems connected by two loops, in a classic pseudoknot topology. The pseudoknot is unusual in that one of the loops consists of only one nucleotide, which spans the major groove of a seven base pair helical stem. Imino proton resonances indicate the hydrogen bonding pattern within the pseudoknot, and two-dimensional NOE spectra provide information that describes many of the structural features. The temperature dependence of the UV absorption and imino proton exchange rates provides insight into the stability of the pseudoknot. A three-dimensional model of the pseudoknot that is consistent with our NMR data is presented, and features that may be important for stabilizing the pseudoknot structure are discussed. A substantial number of other putative RNA pseudoknots described in the literature have sequences and topologies that appear to be related to the T2 and T6 pseudoknots. We propose that these RNAs may be members of a family of pseudoknots related by a similar structural motif, which we refer to as "common pseudoknot motif 1" or CPK1. The bacteriophage T2/T6 pseudoknot can be considered a structural model for the CPK1 family. The common features of the CPK1 pseudoknots are a stem 2 with six or seven base pairs, a loop 1 consisting of a single adenosine, and a variable length stem 1 and loop 2. The first "dangling" nucleotide at the 3' end of the molecule probably stabilizes stem 2. The CPK1 family includes several of the retroviral pseudoknots associated with mRNA frameshifting and readthrough. The work presented here describes the first detailed NMR analysis of an RNA pseudoknot with an entirely natural nucleotide sequence.

Structure of 1,3,5,7-tetranitro-3,7-diazabicyclo-[3.3.0]octane. Structure solution from molecular packing analysis

The structure was solved with the molecular packing program MOLPAK, starting with a molecular mechanics-geometry optimized model of an isolated molecule. The best predicted crystal structures from the MOLPAK procedure were subjected to lattice energy refinement with the WMIN program. The MOLPAK/WMIN-predicted crystal structure, whose cell parameters were closest to the experimental values, gave an initial R of 0.48 for the 173 data to 0 = 25°. Four cycles of least-squares refinement of x, y, z and U gave an R of 0.27 for the 277 data to 0 = 30°. Final R = 0.038, wR = 0.044. There are no unusual intermolecular distances and crystal packing is normal.

Target imaging diagnosis of human brain glioma. Clinical analysis of 40 cases

OBJECTIVE

To establish a method for localization and qualitative diagnosis of glioma.

METHODS

The monoclonal antibody SZ-39 against human glioma was labelled with 131I and injected intravenously into 40 patients with intracranial occupying lesions proved by X-CT. 72 hours after 131I-McAb-SZ39 administration, cranial bone nuclide-imaging agent 99mTc-MDP was injected intravenously, and the patients were examined by SPECT scan with dual nuclide double channel tomography and special software. On radio-immuno-image, the immunocomplex formed by specific conjugation of 131I-McAb-SZ39 with target tissue was red, while the cranial bone incorporated with 99mTc-MDP was green. The location of the immunocomplex area could be identified by the superimposition of the images.

RESULTS

21 patients with positive targeting diagnosis of glioma showed the accuracy rate checked by SPECT was 81%(17/21) and by X-CT 48% (10/21). Seven patients with negative targeting diagnosis showed the accuracy rate checked by SPECT was 86%(6/7) and by X-CT 14% (1/7). Pathologically, the sensitivity of targeting SPECT to glioma was 94.5%(17/18) and that of X-CT 55%(10/18).

CONCLUSIONS

Targeting SPECT examination could be used for localization and qualitative diagnosis of glioma and make up the inadequacy of X-CT in the qualitative diagnosis of atypical incipient and recurrent glioma, meningioma, metastatic carcinoma, and inflammatory lesions of brain.

[Investigation and experimental study on the standards and quality of leech pieces]

It has been confirmed by investigation that Whitmania pigra is the main medicinal breed of leech, and filiform pieces are the best for extraction. The quality of leech processed by 3 different methods has been studied qualitatively and quantitatively in terms of amounts of extraction, TLC, electrophoresis of protein and anti-thrombin action.

Identification of a nef allele that causes lymphocyte activation and acute disease in macaque monkeys

Residues 17 and 18 in nef of SIVmac239 were changed from RQ to YE to create a translated sequence of SRPSGDLYERLLRARGETYGRLLGEVEDGYSQSP from residues 10-43. The YXXL motifs in this context match very well with consensus sequences for SH2 binding domains and are similar to ones present in nef of the acutely lethal pathogen SIVpbj14. The YE variant of SIVmac239, unlike SIVmac239 but like SIVpbj14, replicated well in resting peripheral blood mononuclear cell cultures, caused extensive T lymphocyte activation, and produced an acute disease in rhesus and pigtailed monkeys characterized by severe diarrhea, rash, and extensive lymphoid proliferation in the gastrointestinal tract. The YEnef gene transformed NIH 3T3 cells in culture. Both 239nef and YEnef were found to associate with src in cotransfected COS cells, and both 60 kDa src and 34 kDa nef were phosphorylated at tyrosine in these cells. The extent of tyrosine phosphorylation of 239nef was considerably less than that of YEnef in these assays. These findings identify an important determinant of the SIVpbj14 phenotype, and they provide evidence of a role for nef in signal transduction and cellular activation.