Purification and cloning of PZR, a binding protein and putative physiological substrate of tyrosine phosphatase SHP-2

Overexpression of a catalytically inactive mutant of tyrosine phosphatase SHP-2 in 293 cells resulted in hyperphosphorylation of a glycoprotein specifically associated with the enzyme. The protein has been purified to near homogeneity. Based on the amino acid sequences of peptides obtained from the protein, a full-length cDNA was isolated. The cDNA encodes a protein with a single transmembrane segment and a signal sequence. The extracellular portion of the protein contains a single immunoglobulin-like domain displaying 46% sequence identity to that of myelin P0, a major structural protein of peripheral myelin. The intracellular segment of the protein shows no significant sequence identity to any known protein except for two immunoreceptor tyrosine-based inhibitory motifs. We name the protein PZR for protein zero related. Transfection of the PZR cDNA in Jurkat cells gave rise to a protein of expected molecular size. Stimulation of cells with pervanadate resulted in tyrosine phosphorylation of PZR and a near-stoichiometric association of PZR with SHP-2. Northern blotting analyses revealed that PZR is widely expressed in human tissues and is particularly abundant in heart, placenta, kidney, and pancreas. As a binding protein and a putative substrate of SHP-2, PZR protein may have an important role in cell signaling.

Architectural features of the Salmonella typhimurium flagellar motor switch revealed by disrupted C-rings

The three-dimensional surface topology of rapid-frozen Salmonella typhimurium flagellar hook basal body complexes was studied by stereo-examination of thin-film metal replicas. The complexes contained the extended cytoplasmic structure, composed of the switch complex proteins; FliG, FliM, and FliN. Distinct nanometer-scale element arrays, separated by grooves, defined the outer surface of the cytoplasmic (C-) ring. The number of array elements was comparable to previously determined FliG and FliM copy numbers in the basal body. In addition to basal body complexes lacking C-rings, complexes containing incomplete C-rings were identified. The incomplete C-rings had lost segments of the proximal array. Basal bodies with the distal C-ring array alone were not found. These findings are compatible with the spatial organization of the flagellar switch suggested by previous biochemical data.

[Effects of l-stepholidine on the peripheral vascular dopamine DA1 and DA2 receptor subtypes]

The effects of l-stepholidine(l-SPD) on peripheral vascular dopamine DA1 and DA2 receptors were studied using isolated vascular rings in rabbits. It was shown that (1) l-SPD(0.1-10 mumol.L-1) shifted the dose-response curves to the right in a nonparallel fashion and decreased the maximal response (Emax) of both the fenoldopam(FODA, a selective DA1 agonist)-induced and the propyl-buty-dopamine(PBDA, a selective DA2 agonist)-induced vasorelaxation showing a non-competitive antagonistic action. The pD2 values of l-SPD for FODA in the renal, pulmonary and mesenteric arteries were 5.43, 5.48 and 5.58, respectively. The pD2 values for PBDA in the mesenteric and femoral arteries were 5.35 and 5.89, respectively. The potencies of its antagonistic action were comparable to SCH23390, a selective DA1 antagonist, and to domperidone, a selective DA2 antagonist. (2) l-SPD(0.1-100 mumol.L-1) per se was also found to induce slight but dose-related vasorelaxations in the renal and pulmonary arteries displaying its DA1 agonistic activity. Its pD2 values were 4.98 and 5.02, respectively. However, its Emax were considerably smaller than that of FODA. These results suggest that l-SPD is a mixed peripheral DA1 and DA2 receptor antagonists and weak DA1 receptor agonist with pharmacological property of dual action.

Steroid-resistant asthma: effects of glucocorticoids on interleukin-4 and interleukin-5 gene expression

OBJECTIVE

To investigate the role of interleukin-4 (IL-4) and interleukin-5 (IL-5) in the pathogenesis of steroid-resistant (SR) asthma.

METHODS

Fifteen patients with SR asthma and 15 patients with steroid-sensitive (SS) asthma were selected based on their clinical responses to prednisone therapy. The peripheral blood mononuclear cells (PBMCs) were obtained and incubated with phytohemagglutinin (PHA) in vitro for 48 h in the presence or absence of dexamethasone (10(-7) mol/L). Expressions of IL-4 and IL-5 mRNA in PBMCs were determined by reverse transcription-polymerase chain reaction (RT-PCR), and mRNA positive PBMCs for IL-4 and IL-5 were measured with in situ hybridization using digoxin-labeled cDNA probes.

RESULTS

In the absence of dexamethasone, there was no significant difference in the expressions of IL-4 and IL-5 mRNA between SR and SS asthmatics, and the numbers of mRNA positive cells for IL-4 and IL-5 were also similar between these two groups, however, in the presence of dexamethasone (10(-7) mol/L), expressions of IL-4 mRNA (P < 0.01) and IL-5 mRNA (P < 0.05) were significantly inhibited in SS asthmatics, but not in SR asthmatics (P > 0.05). The numbers of IL-4 and IL-5 mRNA positive cells decreased from 5.50 +/- 1.60 to 2.27 +/- 0.98 (P < 0.01) and from 5.03 +/- 1.29 to 1.67 +/- 0.70 (P < 0.01), respectively in SS asthmatics, but in the patients with SR asthma, there was no significant change in the number of cells expressing mRNA for IL-4 or IL-5.

CONCLUSION

The gene expression of IL-4 and IL-5 in SR asthma was not inhibited by dexamethasone at the concentration of 10(-7) mol/L. It is suggested that the relative unresponsiveness of T cells to glucocorticoids and persistent production of cytokines may be one of the mechanisms of steroid resistance in asthma.

A mutated murine reduced folate carrier (RFC1) with increased affinity for folic acid, decreased affinity for methotrexate, and an obligatory anion requirement for transport function

In an ongoing study of structure-function relationships of the murine reduced folate carrier 1 (RFC1), a glutamate to lysine mutation at amino acid 45 was identified in a methotrexate (MTX)-resistant L1210 clonal variant in which MTX and 5-formyltetrahydrofolate (5-CHO-THF) influx was markedly decreased. The characteristics of the mutated carrier, RFC1-E45K, were studied by cDNA transfection into the murine MTXrA line in which endogenous carrier is not functional. Folic acid influx doubled in the transfectant MTXrA-E45K as compared with L1210 or MTXrA cells; in contrast, MTX and 5-CHO-THF influx was only 14 and 27% that of L1210 cells, respectively. 5-CHO-THF influx in MTXrA-E45K cells was characterized by a 12- and 3.6-fold decrease in influx Vmax and Kt respectively, relative to L1210 cells. The folic acid influx Ki in L1210 cells was more than 50-fold greater than that of MTX based upon inhibition of 5-CHO-THF influx. In comparison, the mutated carrier had comparable affinities for folic acid and MTX in MTXrA-E45K cells due to a 7-fold decrease in the folic acid influx Ki and 7-fold increase in the MTX influx Ki. Transport via native RFC1 is inhibited by a variety of anions in L1210 cells associated with an increase in influx Kt. However, influx of 5-CHO-THF in MTXrA-E45K cells in a HEPES buffer (9 mM chloride) was decreased by 70% due to a 3-fold fall in the Vmax. In the complete absence of chloride (K+-HEPES-sucrose buffer) 5-CHO-THF influx was only 10% that in HBS buffer. 5-CHO-THF influx was restored by addition of chloride, fluoride, or nitrate but not by sulfate, phosphate, or ATP which were all inhibitory over a broad range of concentrations. The data suggest that substitution of a positive for a negative amino acid at position 45 results in the loss of RFC1 mobility in the absence of small inorganic anions that bind to, and neutralize the positive charge on, the lysine residue. Inhibition by higher charged anions may be due to interactions at another carrier site present in both the mutated and wild type carrier. This and other studies suggest that amino acids in the first predicted transmembrane domain play an important role in determining the spectrum of affinities for, and mobility of, RFC1 and is a cluster region for mutations when cells are placed under selective pressure with antifolates that utilize RFC1 as the major route of entry into mammalian cells.

[The role of diet consultation on improvement of the diet nutrition in pregnant women]

OBJECTIVE

To study the improvement of the intakes of various nutrients including protein, fat, carbohydrate, fibers, calcium, iron, zinc et al, in pregnant women after appropriate diet consultation by doctors.

METHODS

100 cases of pregnant women coming to our diet consultation clinic were randomly selected, in which 50 cases (control group) came for the first time and another 50 cases (study group) were for the third visit at least. The diet nutrition of the study group after the second consultation were compared with that before consultation and with concurrent control group.

RESULTS

After diet consultation, except for retinol, the intake of various nutrients, including calorie intake, protein, fibers, magnesium, calcium, phosphorus, iron, zinc, vitamin E, riboflavin, thiamine, nicotinic acid, in study group were significantly improved compared with that of the study group before diet consultation and of the control group (P < 0.01).

CONCLUSION

Diet consultation plays excellent role in promoting scientific and appropriate nutrients intake of pregnant women.

[Relationship between lipometabolic disorder in stroke with TCM syndrome differentiation and typing]

OBJECTIVE

To analyse the relationship between lipometabolic disorder in stroke with TCM Syndrome Differentiation and Typing.

METHODS

The serum lipid, lipoprotein and apo-lipoprotein level of TCM treated group (142 cases) and control group (100 cases) were determined. The patients were subdivided into three Type-groups according to TCM Syndrome Differentiation: Phlegm-Dampness Stagnation (PDS), Yin Deficiency with Yang Hyperactivity (YDYH) and Qi Deficiency with Blood Stasis (QDBS) group.

RESULTS

The results showed that the level of TC, TG, HDL, LDL, apoA1, apoB and apoA1/apoB were significantly different in PDS and QDBS as compared with control group (P < 0.05, P < 0.01, respectively), while lipometabolic disorder of PDS was most serious in TCM Syndrome Differentiation of stroke. The level of TG, apoA1/apoB were significantly different in YDYH in comparing with control group (P < 0.05). While the level of TC, HDL, LDL and apoB were insignificantly different than those of control group (P > 0.05).

CONCLUSIONS

This study showed that lipometabolic disorder of stroke were correlated with Syndrome Differentiation of TCM. Stroke with PDS and QSBS should give removing Phlegm-Dampness, dredging Meridian and removing blood stasis treatment besides routine treatment.

Ginseng improves strategic learning by normal and brain-damaged rats

Adult rats were prepared with either sham or medial prefrontal cortex lesions and administered, beginning on the third post-operative day, either, 0, 40, or 80 mg kg-1 crude ginseng extract suspended in saline daily for the next 30 days. Later, kinetic functions were evaluated on an elevated rotating rod. No long-term influences of the treatments were observed on this task. Significant positive influences of ginseng were observed in the position reversal task. The learning deficits observed in the saline control brain-damaged rats were significantly attenuated in the ginseng-treated animals. An analysis of trial 2 response accuracy across reversals revealed enhanced cognitive abilities (i.e. acquisition of a win-stay, lose-shift strategy) in both the brain damaged and sham control rats administered ginseng. Generally, administration of the higher dose resulted in better performance in the learning paradigm. The exact mechanism responsible for these promising results remains to be discovered. Several possible mechanisms are discussed.

[Detection of hemophilia A carriers by PCR analysis of hind III polymorphism in the factor VIII gene]

OBJECTIVE

To explore a scheme of using PCR analysis in the detection of carriers of Hind III polymorphism of factor VIII gene of hemophilia A.

METHODS

Implicating intron 19 of the factor VIII gene of 6 patients with the hemophilia A and 207 unrelated X-chromosomes were amplified by PCR and were analysed by means of Amp-RFLPs of Hind III.

RESULTS

The incidence of the polymorphic Hind III sites in the given population was found to be 0.29. The frequence of the Hind III heterozygotes in women calculated according to Hardy-Weinberg equation was 0.41, which proved to be informative enough for carrier detection and prenatal diagnosis of hemophilia A. 2 out of 6 families (33%)examined in this study were informative.

CONCLUSION

The new scheme proved to be effective for hemophilia A carrier detection and prenatal diagnosis.

A reduced folate carrier mutation produces substrate-dependent alterations in carrier mobility in murine leukemia cells and methotrexate resistance with conservation of growth in 5-formyltetrahydrofolate

With 5-formyltetrahydrofolate (5-CHO-THF) as the folate source a methotrexate (MTX) transport-deficient murine leukemia cell line, L1210-G1a, was isolated after chemical mutagenesis and MTX selection. This cell line was 10-fold resistant to MTX in comparison to parental L1210 cells, yet the EC50 for 5-CHO-THF was increased by a factor of only 2. The initial uptake of MTX, at a concentration of 1 microM, was decreased by a factor of 40, whereas influx of 5-CHO-THF dropped by a factor of only 8. This difference in initial uptake rates was attributed solely to changes in influx Vmax without a significant change in Km. Whereas the RFC1 mRNA level in L1210-G1a cells was indistinguishable from that of parental L1210 cells, a serine to asparagine substitution was identified at amino acid 46 within the first predicted transmembrane domain. This was a result of a homozygous mutation of G-->A in the genome. Transfection of the mutated RFC1 cDNA into MTXrA cells, which lack functional endogenous carrier, resulted in a clonal derivative MTXrA-S46N. The increase in influx of 5-CHO-THF and 5-CH3THF was 5 and 13 times greater than that for MTX in the transfectant, consistent with the influx ratio in the L1210-G1a line. The functional expression of the mutated RFC1 reduced the growth requirement for 5-CHO-THF by a factor of 30, compared with only a 3-fold decrease in the MTX IC50. This represents the first reported RFC1 mutation that confers resistance to MTX due to a markedly impaired influx with relative conservation of reduced folate transport. The kinetic changes are consistent with a substrate-dependent alteration in carrier mobility that favors reduced folates over MTX. These changes may account for the development of MTX resistance due to impaired drug transport in vivo, allowing tumor cells to meet their folate requirement with 5-CH3THF, the predominant blood folate.

Synthesis, topoisomerase I inhibitory activity and in vitro cytotoxicity of camptothecin derivatives bearing five-membered heterocycle containing 10-substituents

A series of new camptothecin derivatives bearing certain five-membered heterocycles was synthesized and evaluated for in vitro cytotoxic activity. The cytotoxicity results show that camptothecin derivatives bearing pyrrole and thiophene rings were more potent than camptothecin, whereas those bearing furan were less active than camptothecin. Agarose gel electrophoresis shows different inhibitory activities of the camptothecin analogs towards topoisomerase I DNA cleavage. The pyrrole-containing compounds inhibit topoisomerase I DNA cleavage more strongly than camptothecin, but the thiophene and furan compounds do not show any inhibitory activities for DNA cleavage functions of topoisomerase I. Polyacrylamide gel sequencing electrophoresis shows that the pyrrole compounds induce single-strand breaks after incubating with a labeled DNA fragment. The results suggest that the pyrrole compounds fit the compound-enzyme-DNA complex better than camptothecin and the other analogs.

[Math-model of efficient cultivation of Angelica sinensis]

Using two-time general rotation-constitution design, the math-mdele has been founded about Angelica sinensis prodution efficiency and quantity of nitrogen, phosphorus and potassium to use by doing experiments in many different spots and production demonstration for testing and verifying. Accordin to the modle, computer is used to simulate the better, through which people can get fresh Chinese angelica over 500 Kg per mu and also net income over 500 yuan per mu. It shows that this is the best combination. 95% density riliability for this plan is 6860-7600 plants, pure nitrogen 18.75-22.2 Kg, P2O5 9.1-11.1 Kg and K2O 4.46-5.37 Kg One mu. Proportion for nitrogen, phosphorus, potassium is 1:0.49:0.24.

[The effects of Gu Chi Gao on IL-8 in GCF of periodontitis]

In order to find a new treatment of periodontitis, this paper studied the effects of Gu Chi Gao on IL-8 in gingival crevicular fluid (GCF) of periodontitis. One tooth was selected from every patient in 24 patients with adult periodontitis. After supragingival scaling, the patients were divided into two groups randomly. One group was treated with Gu Chi Gao, while the other group was untreated as control group. All patients were examined after one month. GCF samples were collected with 2 mm x 20 mm Whatman I filter paper stripes and IL-8 in the GCF samples were detected by the method of ELISA. The result demonstrated that the levels of GCF and IL-8 in the treated group were lower than that of control group (P < 0.01), it suggests that Gu Chi Gao may inhibit the production of IL-8 and GCF.

Impact of overexpression of the reduced folate carrier (RFC1), an anion exchanger, on concentrative transport in murine L1210 leukemia cells

Transport of reduced folates in murine leukemia cells is mediated by the bidirectional reduced folate carrier (RFC1) and independent unidirectional exit pumps. RFC1 has been proposed to be intrinsically equilibrating, generating transmembrane gradients by exchange with inorganic and organic anions. This paper defines the role of high level carrier expression, through transfection with RFC1 cDNA, on concentrative transport of the folate analog, methotrexate (MTX) in murine L1210 leukemia cells. RFC1 was expressed in the MTXrA line, which lacks a functional endogenous carrier to obtain the MTXrA-R16 clonal derivative. Influx was increased approximately 9-fold in MTXrA-R16 cells without a change in Km. The efflux rate constant was increased by a factor of 5.1 relative to L1210 cells, and this resulted in only a 2.1-fold increase in the steady-state level of free intracellular MTX, [MTX]i, when [MTX]e was 1 microM. The concentrative advantage for RFC1 (the ratio of [MTX]i in MTXrA-R16 to L1210 cells) increased from 1.8 at 0.1 microM MTX to 3.8 at an [MTX]e level of 30 microM. Augmented transport in MTXrA-R16 cells was accompanied by a 2-fold increase in accumulation of MTX polyglutamate derivatives and a approximately 50% decrease in the EC50 for 5-formyltetrahydrofolate and folic acid and the MTX IC50 relative to L1210 cells. These alterations paralleled changes in [MTX]i and not the much larger change in influx at low [MTX]e levels, consistent with the critical role that free intracellular folates and drug play in meeting cellular needs for folates and as a determinant of antifolate activity, respectively. The data indicate that RFC1 produces a large and near symmetrical increase in the bidirectional fluxes of MTX resulting in only a small increase in the transmembrane chemical gradient at low extracellular folate levels. Hence, increased expression of RFC1, alone, may not be an efficient adaptive response to folate deprivation, and other factors may come into play to account for the marked increases in concentrative folate transport which occur when cells are subjected to low folate-selective pressure.

[Comparison of plasma thyroxin and insulin concentrations between 10-day old layer and broiler chickens]

In this study both sexes of 10 day old layer and broiler chickens were used to investigate plasma circulating concentrations of 3,3'-5-triiodothyronine (T3), thyroxine (T4) and insulin by using the radioimmunoassay (RIA) methods. The results were as follows: serum T3 concentration was higher in broilers than that in layers (P < 0.01), especially a significant difference between male strains was seen in this experiment (P < 0.001), and the levels of plasma insulin was significantly higher in male broilers than that in male layers (P < 0.001), however, no clear differences in plasma T4 was seen between strains and sexes (P > 0.05). In addition, there were sex differences in T3 and insulin levels in layers, that is to say, those in the female layers was higher than those in the male layers, but no clear deifference was seen between sexes in broilers. A significant positive correlation between T3, insulin and their weight gained (P < 0.05). The results suggest that the levels of serum T3 and Insulin may influence the various growth rate during early posthatch development in layers and broilers.

[In situ hybridization for interleukin 4 and interleukin 5 messenger RNA in asthma]

The actual mechanism by which a group of asthmatics were resistant to glucocorticoids therapy remains poorly understood. Previous in vitro studies suggested that the pattern of cytokine gene expression may play a role in determining steroid resistance. In the current study, we used the technique of mRNA in situ hybridization to examine whether peripheral blood mononuclear cells (PBMCs) from steroid-resistance (SR) asthmatics vs. Steroid-sensitive (SS) asthmatics expressed different patterns of cytokines, particularly after treatment with steroid. PBMCs from SR patients did not differ significantly from those of SS in terms of their number expressing Interleukin (IL)-4 mRNA and IL-5 mRNA (P > 0.05) by culture alone. There were no differences in the number of PBMCs expressing IL-4 mRNA and IL-5 mRNA (P > 0.05) between incubation in the absence and presence of dexamethasone (DXM, 10(-7) mol/L) in SR. SS patients had a significant dicrease in the number of PBMCs expressing IL-4 mRNA and IL-5 mRNA (P < 0.01) after culture in the presence of DXM as compared with incubation in media alone. Our findings indicate that SR asthma is associated with a dysregulation of the expression of the genes encoding for IL-4 and IL-5.

[9-cis retinoic acid induces apoptosis in HL-60 cells]

OBJECTIVE

To investigate the apoptosis of HL-60 cells induced by 9-cis retinoic acid (9-cis RA), and illustrate the possible molecular mechanism.

METHODS

Apoptosis was detected by morphological observation, DNA electrophoresis and flow cytometric cell cycle analysis. Bcl-2 expression was detected by flow cytometry.

RESULTS

9-cis RA initiated apoptosis of HL-60 cells after inducing them irreversibly commited to differentiation. Bcl-2 was downregulated during the differentiation and apoptosis process. 9-cis RA was more potent than all-trans retinoic acid (ATRA) did in inducing terminal differentiation associated apoptosis and in downregulation of Bcl-2 expression.

CONCLUSION

9-cis RA can induce apoptosis in HL-60 cells. Downregulation of Bcl-2 expression appears to play an important role in the apoptosis of the differentiated leukemic cells.

[Scale-up preparation of hydrophobic interaction chromatographic packing materials based on inorganic matrix]

Based on inorganic matrix controlled pore glass (CPG) and macro-pore silica sphere, by using polyethylene glycol (PEG 1000) as a ligand, a preparation method of hydrophobic interaction chromatographic (HIC) packing material was improved by adding a proper catalyst during the bonding process. The packing material can be synthesized in a scale-up batch, for example 150g for each batch, both for analytical and preparative columns. The retention of proteins, such as cytochrome C (Cyt-C), chymotrypsingen-A (Chy-A), lysozyme (Lys) and ribonuclease(Rnase), is increased with the increasing of (NH4)2SO4 concentration in the eluant 2.5 mol/L of salt concentration for the mobile phase was chosen by considering the separation efficiency and equipment life. After comparing the effect of pH for the retention of proteins it is found that the proteins are well separated at pH 7. The time of linear gradient elution program was optimized in considering the separation efficiency and speed. It is better to take 30 minutes of the gradient program for the separation. Six standard proteins can be well separated with the high-performance HIC column in the linear gradient elution program from 2.5 to 0 mol/L of (NH4)2SO4 in 50 mmol/L of phosphate buffer solution within 30 minutes. Cyt-C, Rnase, Lys and Chy-A can be separated by the HIC column based on CPG matrix. Six proteins, Cyt-C, Rnase, Lys, Chy-A, insulin(Ins) and lipase (Lip) can be well separated on the column based on silica matrix with gradient elution program. The recovery of trypsin detected with BAEE method is over 95% after purification with the HIC column.

[Somatostatin and its secretory cells in tumor surrounding mucosa in colorectal cancer patients and its significance]

The somatostatin (SS) levels in tumor surrounding mucosae were determined by RIA, and the SS secretory cells in these tissues were observed by immunocytochemistry in colorectal cancer patients. The mean SS level was higher in cancer-adjacent mucosa (CAM, 0-2 cm from the tumor) than in cancer-distant mucosa (CDM, about 5 cm from the tumor), and in CAM without atypical hyperplasia than in such mucosa with different grades of atypical hyperplasia (P < 0.01). In CAMs, there was a very significant negative correlation between the SS level and cell dysplasia (P < 0.01). The form and location of SS cells in all tumor surrounding mucosae were similar to the normal. Both the mean SS cell number and total positive degree were very significantly higher in CAM than CDM (P < 0.01). SS levels in CAMs were correlated positively with the SS cell numbers and the total positive degrees in CAM (P < 0.01). It is concluded that the elevation of SS level in CAM is mainly caused by the increase of SS cells, which secrete more SS. The change of SS in colorectal cancer surrounding mucosa may play an important role in inhibiting the development of CAM atypical hyperplasia or the tumor, and is a local defensive reaction in the body.

[Toxoplasmosis infection in pregnant women in Lanzhou]

OBJECTIVE

To investigate toxoplasmosis (TOX) infection in pregnant women.

METHODS

The blood samples from 1,250 pregnant women were tested by indirect hemaglutination (IHA) for TOX. 1,327 normal cases were included in control group.

RESULTS

The infection rate of TOX was 7.28% and 8.14% in the study and control group respectivity. There was no significant difference between the study group and control group (P > 0.05). There was no marked relationship between various age groups. (P > 0.05). No significant difference was noted in three gestational periods. Most pregnant women with of TOX infection were active and recent.

CONCLUSION

Pregnancy did not increase the chance of TOX infection.

The refined structure of human rhinovirus 16 at 2.15 A resolution: implications for the viral life cycle

BACKGROUND

Rhinoviruses belong to the picornavirus family and are small, icosahedral, non-enveloped viruses containing one positive RNA strand. Human rhinovirus 16 (HRV16) belongs to the major receptor group of rhinoviruses, for which the cellular receptor is intercellular adhesion molecule-1 (ICAM-1). In many rhinoviruses, one of the viral coat proteins (VP1) contains a hydrophobic pocket which is occupied by a fatty acid-like molecule, or so-called 'pocket factor'. Antiviral agents have been shown to bind to the hydrophobic pocket in VP1, replacing the pocket factor. The presence of the antiviral compound blocks uncoating of the virus and in some cases inhibits receptor attachment. A refined, high-resolution structure would be expected to provide further information on the nature of the pocket factor and other features previously not clearly identified.

RESULTS

The structure of native HRV16 has been refined to a resolution of 2.15 A. The hydrophobic pocket in VP1 is observed in two alternative conformations. In one of these, the pocket is filled by a pocket factor and the protein structure is similar to virus-antiviral compound complexes. In the other conformation, the hydrophobic pocket is collapsed and empty. RNA bases stack against both a tryptophan and a phenylalanine residue on the internal surface of the viral capsid. Site-directed mutagenesis of the tryptophan, which is conserved across the picornaviruses, to nonconservative residues results in non-viable virus. Five symmetry-related N termini of coat protein VP4 form a ten-stranded, antiparallel beta barrel around the base of the icosahedral fivefold axis. The N termini of VP1 are amphipathic alpha helices, which stack on the outside of this beta barrel. The N termini of VP1 and VP4 have not been observed previously in rhinovirus structures.

CONCLUSIONS

The observation of a partially occupied hydrophobic pocket in HRV16 forms a missing link between HRV14, which is always observed with no pocket factor in the native form, and rhinovirus 1A and other picornaviruses (e.g. poliovirus, coxsackievirus) which contain pocket factors. The pocket factor molecules probably regulate viral entry, uncoating and assembly. Picornavirus assembly is known to proceed via pentamers, therefore, the interaction of RNA with the conserved tryptophan residues across twofold axes between pentamers may play a role in picornavirus assembly. The positioning of a cation on the icosahedral fivefold axes and the structure of the N termini of VP4 and VP1 around these axes suggest a mechanism for the uncoating of rhinoviruses.

Enhanced DNA alkylation activities of Hoechst 33258 analogues designed for bioreductive activation

A series of analogues of Hoechst 33258, designed to be subject to bioreductive activation, were synthesized, and interactions between these compounds and pBR322 DNA were investigated. Compounds containing a quinone group reacted with DNA via two possible pathways in the presence of reductants NADH or NADPH: radical cleavage and DNA alkylation. The corresponding dimethoxy compounds, which are not subject to reduction, showed very weak DNA binding ability. The strength of alkylation reaction of the quinone derivatives is related to leaving group ability. Furthermore, the quinone compounds preferentially alkylate DNA at 5'-CG and TG sequences rather than at the AT sites preferred as binding sites of Hoechst 33258.

[The expression of IL-1 alpha gene in gingival tissue]

IL-1 is secreted by a variety of cells and plays an important role in the network of cytokines. In this study, the expression of IL-1 alpha in gingival tissue was determined with reverse transcription-polymerase chain reaction (RT-PCR). The PCR-product was confirmed by DNA sequencing. The results showed that IL-1 alpha transcription was detected in all 5 inflammatory gingival tissue samples, but it was not delected in the normal gingival tissue samples and in the samples after treatment. These findings suggested that IL-1 alpha may be a specific indicator of periodontal disease, and a potential mediator in pathogenesis of periodontitis.

Camptothecin and minor-groove binder hybrid molecules: synthesis, inhibition of topoisomerase I, and anticancer cytotoxicity in vitro

The synthesis, characterization, inhibitory activity against topoisomerase I, and biological evaluation of a series of 14 camptothecin derivatives of polypyrrolecarboxamide (lexitropsin) conjugates of two structural classes: (A) camptothecin-NHCO-lexitropsin 44-51 and (B) camptothecin-CONH-lexitropsin 38-43 are described. All 16 compounds tested, 14 conjugates plus two functionalized camptothecin controls, inhibit topoisomerase I in the concentration range 1.12-16.6 microM that divide into three distinct categories based on activity. The most active enzyme inhibitors belong to structure class A with either cationic dimethylaminium or neutral amide end groups. Generally class B conjugates are less effective in inhibiting topoisomerase I. Cytotoxic potencies of the drugs was tested against four representative human tumor cell lines: SKOV3, SKLVB, HT29, and KB. All 16 drugs gave measurable IC50 values against the KB cell line and fell into two categories with IC50 values of 0.049-0.66 microM (largely structure class B) and 1.0-48 microM (largely class A). Thus the class B conjugates, while less potent against the enzyme, contain two of the most potent drugs, 38 and 39, against KB cell lines. In contrast, in the case of the cell lines SKOV3 and HT29 there was a general correlation between the better topoisomerase inhibitors and their cell cytotoxicities.

Cations in human rhinoviruses

All known crystal structures of rhinoviruses have some uninterpreted electron density on their fivefold axes at a distance of about 152 +/- 3 A from the viral center. This density had been assumed to be a Ca2+ ion, based on its shape, height, and the presence of Ca2+ ions in the crystallization solutions. Difference electron density maps between EGTA-soaked crystals of human rhinovirus 14 (HRV14), as well as HRV16, and their corresponding native structures show that this density is an EGTA-chelatable ion. Analysis of the coordination geometry indicates that the ions in HRV3, HRV14, and HRV1A could be Ca2+ and the ion in HRV16 might be Zn2+. These cations may play a role in regulation of rhinovirus stability, although the loss of the ion itself does not seem sufficient to lead to viral disassembly.