Molecular mechanism of endothelial growth arrest by laminar shear stress

This study was designed to elucidate the mechanism underlying the inhibition of endothelial cell growth by laminar shear stress. Tumor suppressor gene p53 was increased in bovine aortic endothelial cells subjected to 24 h of laminar shear stress at 3 dynes (1 dyne = 10 microN)/cm(2) or higher, but not at 1.5 dynes/cm(2). One of the mechanisms of the shear-induced increase in p53 is its stabilization after phosphorylation by c-Jun N-terminal kinase. To investigate the consequence of the shear-induced p53 response, we found that prolonged laminar shear stress caused increases of the growth arrest proteins GADD45 (growth arrest and DNA damage inducible protein 45) and p21(cip1), as well as a decrease in phosphorylation of the retinoblastoma gene product. Our results suggest that prolonged laminar shear stress causes a sustained p53 activation, which induces the up-regulation of GADD45 and p21(cip1). The resulting inhibition of cyclin-dependent kinase and hypophosphorylation of retinoblastoma protein lead to endothelial cell cycle arrest. This inhibition of endothelial cell proliferation by laminar shear stress may serve an important homeostatic function by preventing atherogenesis in the straight part of the arterial tree that is constantly subjected to high levels of laminar shearing.

Mutagenicity studies of benzidine and its analogs: structure-activity relationships

The Ames Salmonella/microsome assay was employed to test the mutagenicity of benzidine and its analogs using strains TA98 and TA100 in the presence and absence of Aroclor 1254-induced rat S9 mix. 3,3'-Dichlorobenzidine-2HCl and 4,4'-dinitro-2-biphenylamine were directly mutagenic to TA98, while 4,4'-dinitro-2-biphenylamine was directly mutagenic to both TA98 and TA100 in the absence of S9 mix. 2-Aminobiphenyl, 3-aminobiphenyl, and 3,3'-5,5'-tetramethylbenzidine were not mutagenic in either strains in the presence or absence of S9. In the presence of S9 mix, 4-aminobiphenyl, benzidine, 3, 3'-dichlorobenzidine-2HCl, 3,3'-dimethoxybenzidine, 3,3'-4, 4'-tetraaminobiphenyl, o-tolidine, N, N-N', N'-tetramethylbenzidine, and 4,4'-dinitro-2-biphenylamine were mutagenic to TA98; 4-aminobiphenyl, 3,3'-dichlorobenzidine-2HCl, 3, 3'-dimethoxybenzidine, and 4,4'-dinitro-2-biphenylamine were mutagenic to TA100. Physicochemical parameters of these compounds including oxidation potentials, the energy difference between the lowest unoccupied molecular orbital and the highest occupied molecular orbital, ionization potentials, dipole moment, relative partition coefficient, and basicity did not correlate with their bacterial mutagenic activities.

Expression of capsid [correction of caspid] protein VP1 for use as antigen for the diagnosis of enterovirus 71 infection

To produce enterovirus 71 antigen for diagnostic purposes, the gene encoding the entire capsid protein VP1 was amplified by reverse transcription-polymerase chain reaction (RT-PCR), cloned and expressed in Escherichia coli as a poly-histidine fusion protein. Western blotting experiments with sera from patients with enterovirus 71 infection indicated that immunoglobulin G (IgG) and IgM antibodies bound to a single polypeptide VP1. According to these results, IgM anti-VP1 appeared in sera of patients with a symptomatic enterovirus 71 acute infection, whereas IgG anti-VP1 was present in sera of past infection. This finding suggests that detecting IgG and IgM immune responses against linear epitopes of recombinant VP1 is an effective means of determining the different phases of enterovirus 71 infection. In addition, sera containing coxsackie virus 16 (CA16) antibodies did not cross-react with the recombinant VP1 of enterovirus 71, despite the homology between VP1 proteins of both viruses. Comparison with reference PCR and neutralization assays showed these antibody tests to be appropriate for the serodiagnosis of enterovirus 71 infection.

B-cell commitment, development and selection

Here we review three areas in B-cell development in the mouse, with a focus on relevance to B-1/CD5+ B cells. Multiparameter flow cytometry has allowed the dissection of intermediate stages of developing B cells, both in fetal liver and bone marrow. In the first area, we present recent work that has delineated a fraction of pre-pro-B cells, committed to the B lineage, but lacking any immunoglobulin rearrangements. Next, the role of the pre-B-cell receptor in B-cell repertoire selection has become clear in the past few years, but we present work suggesting that the action of this process during fetal life is different, resulting in selection of a very distinct repertoire compared with adult. Finally, we describe a new VH3609 antithymocyte Ig transgenic mouse model system that has provided the first definitive evidence for the role of self-antigen in development and maintenance of natural autoreactive B cells.

Purification and characterization of neutral sphingomyelinase from Helicobacter pylori

Phospholipase activities of human gastric bacterium, Helicobacter pylori, are regarded as the pathogenic factors owing to their actions on epithelial cell membranes. In this study, we purified and characterized neutral sphingomyelinase (N-SMase) from the superficial components of H. pylori strains for the first time. N-SMase was purified 2083-fold with an overall recovery of 37%. The purification steps included acid glycine extraction, ammonium sulfate precipitation, CM-Sepharose, Mono-Q, and Sephadex G-75 column chromatography. Approximate molecular mass for the native N-SMase was around 32 kDa. When N-omega-trinitrophenylaminolauryl sphingomyelin (TNPAL-SM) was used as a substrate, the purified enzyme exhibited a K(m) of 6.7 microM and a V(max) of 15.6 nmol of TNPAL-sphingosine/h/mg of protein at 37 degrees C in 50 mM phosphate-buffered saline, pH 7.4. N-SMase reaches optimal activity at pH 7.4 and has a pI of 7.15. The enzyme activity is magnesium dependent and specifically hydrolyzed sphingomyelin and phosphatidylethanolamine. The enzyme also exhibits hemolytic activity on human erythrocytes. According to Western blot analysis, a rabbit antiserum against purified N-SMase from H. pylori cross-reacted with SMase from Bacillus cereus. Sera from individuals with H. pylori infection but not uninfected ones recognizing the purified N-SMase indicated that it was produced in vivo. In enzyme-linked immunosorbent assays, the purified N-SMase used as an antigen was as effective as crude protein antigens in detecting human antibodies to H. pylori.

Is there immunity to Schistosoma japonicum?

The Oriental schistosome, Schistosoma japonicum, unlike the other two major schistosomes that infect humans (S. mansoni and S. haematobium), is a zoonotic species. The transmission dynamics and the potential effects of host-related regulatory factors, including immunity, are likely to be distinct for this parasite. Here, Allen Ross and collaborators from Australia, China and the Philippines discuss recently published and established epidemiological and laboratory data bearing on anti-infection immunity to Asian schistosomiasis, and contrast these findings with the emerging picture of development of anti-infection immunity against the African schistosomes. Implications for vaccines and other control strategies for schistosomiasis japonica are also discussed.

Epidemiology of Schistosoma japonicum in China: morbidity and strategies for control in the Dongting Lake region

Dongting Lake, covering a very large surface water area of 2691km(2), is located in Hunan Province in the southern part of the People's Republic of China. It is the second-largest freshwater lake in China and plays an important role in regulating the amount of water in the Yangtze River, China's longest river. The annual water level of the lake changes by as much as 15m, rising in summer and falling in winter. Asian schistosomiasis has been endemic in the Dongting Lake region for centuries and it has had a devastating effect on the public health of the local people. After a difficult struggle for more than four decades, a concerted programme, supported by the World Bank Loan and instigated in 1992, has resulted in remarkable progress in the control of the disease in many endemic areas of the region. However, the great challenge remains to consolidate and maintain the achievements made to date. The Schistosoma japonicum intermediate host (Oncomelania hupensis hupensis) snail habitats are huge, estimated at 1768km(2) in 1996; these are increasing at a rate of 34.7km(2) annually due to high silt deposition from the Yangtze River itself and from the connecting rivers in Hunan province, and construction of embankments in the Dongting Lake region. It is anticipated that the construction of the Three Gorges Super Dam, the largest engineering project ever undertaken, will substantially extend the range of the snail habitats and increase the number of new schistosomiasis cases. In many areas, human re-infections with S. japonicum after drug (praziquantel) treatment remain unacceptably high (up to 20% of those treated are re-infected annually) due to occupational (mainly fishing) water contact. This paper reviews the history and the current status of schistosomiasis control in the lake region, it explores the epidemiological factors which influence the prevalence of the infection and the disease it causes, and it provides insight into future approaches to control which might finally eradicate the infection.

Two-year impact of praziquantel treatment for Schistosoma japonicum infection in China: re-infection, subclinical disease and fibrosis marker measurements

We studied a community cohort of 193 individuals exposed to endemic Schistosoma japonicum infection in the Dongting Lake region of China to assess subclinical morbidity and the 2-year benefit of curative therapy (praziquantel) administered in 1996. Prevalence and intensity of S. japonicum infection before treatment were 28% and 192 eggs per gram faeces (epg), respectively. Two years after cure, 22% of the cohort were re-infected, but with a lighter intensity (67 epg). Sixty-four subjects (37%) showed significant improvement in ultrasound parenchyma images after treatment and 51 subjects (54%) showed significant improvement of periportal fibrosis. Left-lobe enlargement also reversed (P < 0.05) and splenomegaly reversed in 6 of 8 cases and developed in only 1. Two years post-treatment a dilated portal vein became less frequent, but the decline was not significant (16% vs 11%, P < 0.05). The serum levels of laminin and collagen IV associated with re-infection and intensity and hyaluronic acid levels correlated with ultrasound findings (P < 0.01). Overall, treatment induced a marked decrease in subclinical hepatosplenic morbidity attributable to S. japonicum although low-intensity re-infection after treatment remained relatively frequent. Stratified analysis and logistic models evaluated potential confounding factors for assessment of treatment effects on hepatic fibrosis. S. japonicum infection and moderate-heavy alcohol intake interacted: improvement in parenchymal morbidity was impeded among drinkers (P < 0.05). Chemotherapy focused on at-risk residents controls prevalent subclinical hepatic fibrosis but re-infection indicates the need for complementary control strategies.

Oxidation of 2,4-dinitrophenol by hydrogen peroxide in the presence of basic oxygen furnace slag

A treatment process was developed when basic oxygen furnace slag (BOF slag) and hydrogen peroxide were used to oxidize 2, 4-dinitrophenol from an aqueous solution. BOF slag, final waste slurry from steel making plants, contains about 12.5% by weight of ferrous oxide. In an acid solution, BOF slag can be dissociated to produce ferrous ions and react with hydrogen peroxide to produce hydroxyl radicals and oxidize 2,4-dinitrophenol. The results of the research demonstrated that the process had a significant capacity for oxidation of 2,4-dinitrophenol from the aqueous phase. Various factors critical to the oxidation of 2,4-dinitrophenol were studied, including hydrogen peroxide concentration, concentration of BOF slag, initial concentration of 2,4-dinitrophenol, and pH value of solution. Experimental results proved that 100 mg/L 2, 4-dinitrophenol and its oxidation intermediate could be totally decomposed within 60 min by 10 g/L BOF slag, 0.18 g/L hydrogen peroxide and pH 2.8 +/- 0.2. The optimum hydrogen peroxide concentration for degradation of 100 mg/L of 2,4-dinitrophenol is between 0.09 g/L and 0.18 g/L as 10 g/L BOF slag in the solution of pH 2.8 +/- 0.2. A hydrogen peroxide concentration higher than 0.18 g/L is disadvantageous to the oxidation process. The oxidation efficiency increased with the increase of BOF slag concentration at 0.18 g/L hydrogen peroxide dose. The best pH value of the solution is in the vicinity of 2.8. An oxidation reaction mechanism was proposed for predicting the concentration changes of 2, 4-dinitrophenol, ferrous ion, and hydrogen peroxide.http://link. springer-ny.com/link/service/journals/00244/bibs/37n4p427.++ +html</HEA

A 2-year prospective study in China provides epidemiological evidence for resistance in humans to re-infection with Schistosoma japonicum

In 1996, 250 people living in the Dongting-Lake region of China were selected for a 2-year study. All had been or were infected with Schistosoma japonicum. All were treated with praziquantel, although eggs of S. japonicum were only detected in stool samples from 75 of the subjects. In 1998, 213 (85.5%) of these subjects, then with a mean (S.D.) age of 40.2 (14.2) years, provided stool samples for final assessment. Forty-nine (23%) of the 213 were found to be re-infected in 1998, with a geometric mean intensity of infection among the infected of 64.5 eggs/g faeces. The rate of re-infection was highest among those aged < 10 years, declining with increasing age, and higher in males than females (27.3% v. 8.3%; P < 0.005). The mean intensity of infection among the infected males was also higher than that among the infected females [72.4 (4.8) v. 17.8 (2.5) eggs/g; P < 0.005]. Water contact by the subjects was estimated from activity diaries, for 141 days over the 2-year study period, and expressed as skin exposure, in m2-min/day. The mean exposure of a group of subjects was calculated by detransforming the mean of the fourth-root-transformed (i.e. normalized) values for the exposures of each subject within the group. Overall, the 213 individuals had a mean exposure of 6.2 m2-min/day. Differences in occupation led to males having much higher mean water exposures than females (9.2 v. 1.1 m2-min/day). As there was an inverse association between age-specific exposure and age-specific re-infection intensity, the marked reduction seen in intensity of re-infection with increasing age is not attributable to decreasing exposure to water. Instead, the results of this 2-year cohort study provide evidence for age-dependent resistance to re-infection with S. japonicum. The 213 subjects who were followed up were classified, according to epidemiological outcome at the end of the study and the data on water contact, as 'susceptible' (N = 49; 23%), 'insusceptible' (N = 29; 13.6%) or of 'uncertain status' (N = 135; 63.4%). Thus, 78 subjects who are potentially informative in terms of immunogenetics were identified. Further investigation of these individuals should help to shed some light on the role of immunogenetic status in human immunity to Schistosoma japonicum.

Production of interleukin-10 by peripheral blood mononuclear cells from residents of a marshland area in China endemic for Schistosoma japonicum

Interleukin-10 (IL-10) cytokine production was assessed using peripheral blood mononuclear cells (PBMC) from 67 individuals living in an area endemic for schistosomiasis japonica in China (Dongting Lake, Hunan Province), and 11 control subjects from a non-endemic part of the same Province. Production of IL-10 was measured following in vitro stimulation of PBMC using whole parasite extract (SWAP) or a panel of recombinant Schistosoma japonicum antigens (22-kDa tegumental membrane-associated antigen, glyceraldehyde-3-phosphate dehydrogenase, paramyosin, 14-kDa fatty acid-binding protein and 28-kDa glutathione S-transferase) which are of recognized interest in the development of protective immunity to schistosomiasis. Significantly, PBMC isolated from the exposed population compared with the non-exposed population produced higher levels of IL-10. There was a trend towards higher mean levels of IL-10 release in putatively resistant (insusceptible) (consistently egg negative but highly exposed) individuals compared with susceptible (egg-positive) subjects from the exposed population. Analysis of individual exposure (the duration of water contact and the percent body surface area in contact with water, expressed as m2 h/day) vs. IL-10 production indicated a weak but consistent and statistically significant inverse correlation, with lower levels of exposure being associated with higher levels of IL-10. These results suggest an association between IL-10 production and resistance to S. japonicum in subjects from this Chinese population exposed to infection.

Antibody isotype responses, infection and re-infection for Schistosoma japonicum in a marshland area of China

Antibody isotype responses to adult worm antigen (AWA) of Schistosoma japonicum and two recombinant proteins (paramyosin (PMY) and a 22 kDa tegumental membrane-associated antigen (TEG)) were analyzed in 137 individuals from an area moderately endemic for schistosomiasis in the Dongting Lake region, Hunan Province, China. The prevalence and geometric mean (GM) intensity of infection before the implementation of curative chemotherapy were 28.5% and 234.4 epg, respectively, but 9 months after treatment the prevalence (6.6%) and intensity (38.3 epg) had decreased. There was no significant difference in either the prevalence or intensity of infection between males and females. Specific IgG (total), IgG4, IgG2, IgA and IgE responses to AWA, PMY and TEG were measured by ELISA. Males produced significantly (P < 0.05) more anti-AWA total IgG, IgE, IgA, IgG4 and IgG2 antibodies, and anti-TEG IgG2 antibody than their female counterparts. The OD450 levels of anti-AWA, PMY and TEG antibody isotypes did not present clear age-dependent trends except for peak levels of anti-AWA IgG4 antibodies evident among subjects 20-29 years of age. The total IgG and IgG4 antibody profiles against AWA correlated well with current S. japonicum infections while anti-AWA IgG2, IgA and IgE antibodies did not show such an association. Anti-AWA-specific IgE antibody levels were positively correlated (r = 0.55) with anti-AWA specific IgG4 antibody levels. In addition, the overall percentage of responders (using a cut-off value obtained from normal controls) to all isotypes to AWA were higher than those observed for both the recombinant antigens. Only 18.2%, 16.8% and 7.3% of the study population were IgE responders to AWA, PMY and TEG. A longer follow-up period is required before we can more fully understand the role of IgE, if any, in protective immunity against schistosomiasis japonica.

Mechanotransduction in response to shear stress. Roles of receptor tyrosine kinases, integrins, and Shc

Shear stress, the tangential component of hemodynamic forces, activates many signal transduction pathways in vascular endothelial cells. The conversion of mechanical stimulation into chemical signals is still unclear. We report here that shear stress (12 dynes/cm2) induced a rapid and transient tyrosine phosphorylation of Flk-1 and its concomitant association with the adaptor protein Shc; these are accompanied by a concurrent clustering of Flk-1, as demonstrated by confocal microscopy. Our results also show that shear stress induced an association of alphavbeta3 and beta1 integrins with Shc, and an attendant association of Shc with Grb2. These associations are sustained, in contrast to the transient Flk-1. Shc association in response to shear stress and the transient association between alphavbeta3 integrin and Shc caused by cell attachment to substratum. Shc-SH2, an expression plasmid encoding the SH2 domain of Shc, attenuated shear stress activation of extracellular signal-regulated kinases and c-Jun N-terminal kinases, and the gene transcription mediated by the activator protein-1/12-O-tetradecanoylphorbol-13-acetate-responsive element complex. Our results indicate that receptor tyrosine kinases and integrins can serve as mechanosensors to transduce mechanical stimuli into chemical signals via their association with Shc.

A dominant-negative pleiotrophin mutant introduced by homologous recombination leads to germ-cell apoptosis in male mice

Pleiotrophin (PTN) is an 18-kDa heparin-binding secretory growth/differentiation factor for different cell types. Its gene is differentially expressed in both mesenchyme and central nervous system during development and highly expressed in a number of different human tumors. Recently, a PTN mutant was found to act as a dominant-negative effector of PTN signaling. We have now used homologous recombination to introduce the dominant-negative PTN mutant into embryonic stem cells to generate chimeric mice. All highly chimeric male mice with germinal epithelium exclusively derived from embryonic stem cells with the heterologous PTN mutation were sterile. Their testes were uniformly atrophic, and the spermatocytes were strikingly apoptotic at all stages of development. The results support a central role of PTN signaling in normal spermatogenesis and suggest that interruption of PTN signaling may lead to sterility in males.

Selective effects of alfuzosin and doxazosin with intraduodenal administration on urethral pressure of cats

AIM

To observe the selective effects of alfuzosin (Alf) and doxazosin (Dox) on the urethral pressure by different administration routes.

METHODS

The urethral pressure of the anesthetized cat was increased by electric stimulation of the hypogastric nerve. The different effects of Alf or Dox on the arterial blood pressure and urethral pressure between intraduodenal administration (i.d.) and intravenous infusion (i.v.) were compared.

RESULTS

When the hypogastric nerve was stimulated by electric stimulation (10 Hz, 25 V), the ratios of ED20(BP)/ED50(UP) i.d. to ED20(BP)/ED50(UP) i.v. were 10.9:4.3 for Alf, and 3.1:2.1 for Dox. The reduction in urethral pressure induced by i.d. Alf was greater than that by i.v. Alf. Dox did not show any difference in its effects by 2 administration routes.

CONCLUSION

Intraduodenal administration of Alf, but not Dox, selectively decreased the urethral pressure elevated by electric stimulation. The uroselectivity of i.d. Alf was not due to the species difference in its bioavailability and biotransformation.

Dominant frequency uncertainty analysis of EEG alpha activity in pilots with transient ischemic attacks

Objective. To study the characteristics of EEG after transient ischemic attack and to offer reference for screening procedure of aircrew and astronaut selection. Method. The dominant frequency uncertainty of alpha band EEG in 12 pilots (males; age 30 +/- 5) with transient ischemic episodes in middle cerebral artery (MCA) territories and in 20 normal healthy pilots was analyzed with frequency-fluctuation analysis. Result. The dominant probability of the main frequency coinciding with sites affected by transient ischemic attack (TIA) in patient pilots was higher than that in healthy pilots (P<0.01), and the dominant probability ratio logarithmic index I >or= 0 in all patient pilots with normal EEG, but I<0 in all healthy pilots. It was also found that not only I >or= 0, but the second component shifted to lower frequency (8 Hz) in patients with slight focal EEG alterations, i.e. slowing of frequency. The relative entropy values (percentage) were decreased significantly in pilots with TIA as compared with healthy pilots (P<0.05). Conclusion. The dominant frequency uncertainty analysis of alpha band showed clear superiority of computerized evaluation over routine visual assessment for the diagnosis of minor cerebral ischemia. It offers not only a possibility of studying pathophysiological functional parameter, but also the reference for screening procedure in aircrew and astronaut selection.

Glycyl-glutamine-enriched long-term total parenteral nutrition attenuates bacterial translocation following small bowel transplantation in the pig

BACKGROUND

Improvements in immunosuppression, operative procedure, and posttransplant management have made clinical small bowel transplantation (SBT) feasible. Ischemia and reperfusion injury, total parenteral nutrition (TPN), and devoidment of enteral feeding lead to graft atrophy, gut barrier dysfunction, and bacterial translocation. Glutamine (Gln) is the principal fuel for the enterocyte. The influence of Gln dipeptide-supplemented TPN, especially long-term TPN, on intestinal graft permeability and bacterial translocation is not clear following SBT in the large animal model. Therefore, we studied the effect of glutamine dipeptide, glycyl-glutamine (Gly-Gln), on bacterial translocation following SBT in the pig, which has a physiology similar to humans.

MATERIALS AND METHODS

The outbred pigs underwent segmental small bowel autotransplantation and were divided into two groups. In the STPN group (n = 5), the animal received standard TPN devoid of Gly-Gln for 28 days. In the GTPN group (n = 5), the animal received isonitrogenous (0.3 g/kg.day) and isocaloric (33 kcal/kg.day) TPN solution with 2% Gly-Gln for 28 days.

RESULTS

At the end of the experiment, Gly-Gln-enriched TPN could maintain the plasma Gln level, graft mucosal Gln and protein concentrations, and skeletal muscle Gln and protein concentrations. Gly-Gln-enriched TPN significantly decreased the bacterial number of mesenteric lymph nodes in the liver and spleen and intestinal permeability to 99mTc-DTPA. There were no significant differences in body weight gain.

CONCLUSIONS

The Gly-Gln-enriched long-term TPN may maintain the plasma Gln level, mucosal and muscle Gln, and protein concentrations and attenuate the intestinal permeability to 99mTc-DTPA and bacterial translocation following small bowel transplantation in the pig.

Phthalocyanine 4 (Pc 4) photodynamic therapy of human OVCAR-3 tumor xenografts

Photodynamic therapy (PDT) is a cancer treatment modality utilizing a photosensitizer, light and oxygen. Photodynamic therapy with Photofrin has been approved by the U.S. Food and Drug Administration for treatment of advanced esophageal and early lung cancer. Because of certain drawbacks associated with the use of Photofrin, there is a need to identify new photosensitizers for human use. The photosensitizer Pc 4 (HOSiPc-OSi[CH3]2[CH2]3N[CH3]2) has yielded promising PDT effects in many in vitro and in vivo systems. The aim of this study was to assess the usefulness of Pc 4 as a PDT photosensitizer for a human tumor grown as a xenograft in athymic nude mice. The ovarian epithelial carcinoma (OVCAR-3) was heterotransplanted subcutaneously in athymic nude mice. Sixty mice bearing OVCAR-3 tumors (approximately 80-130 mm3) were divided into six groups of 10 animals each, three for controls and three for treatment. The Pc 4 was given by tail vein injection, and 48 h later a 1 cm area encompassing the tumor was irradiated with light from a diode laser coupled to a fiberoptic terminating in a microlens (lambda = 672 nm, 150 J/cm2, 150 mW/cm2). Tumors of control animals receiving no treatment, light alone or Pc 4 alone continued to grow. Of animals receiving 0.4 mg/kg Pc 4 and light, one (10%) had a complete response and was cured (no regrowth up to 90 days post-PDT), while all others (90%) had a partial response and were delayed in regrowth. Of animals receiving 0.6 mg/kg Pc 4 and light, eight (80%) had a complete response, and two of these were cured. Of animals receiving 1.0 mg/kg Pc 4 and light, six (60%) had a complete response, and two of these were cured. In additional experiments, tumors from animals treated with Pc 4 (1 mg/kg) and light were removed 15, 30, 60 and 180 min post-PDT, and from these tumors DNA and protein were extracted. Agarose gel electrophoresis revealed the presence of apoptotic DNA fragmentation as early as 15 min post-PDT. Western blotting showed the cleavage of the 116 kDa native poly(ADP-ribose) polymerase (PARP) into fragments of approximately 90 kDa, another indication of apoptosis, and the presence of p21/WAF1/CIP1 (p21) in all PDT-treated tumors. These changes did not occur in control tumors. Pc 4 appears to be an effective photosensitizer for PDT of human tumors grown as xenografts in nude mice. Early apoptosis, as revealed by PARP cleavage, DNA fragmentation and p21 overexpression, may be responsible for the excellent Pc 4-PDT response. Clinical trials of Pc 4-PDT are warranted.

Fluid shear stress activation of IkappaB kinase is integrin-dependent

Vascular endothelial cells (ECs), forming a boundary between the circulating blood and the vessel wall, are constantly subjected to fluid shear stress due to blood flow. The aim of this study was to determine the role of the recently identified IkappaB kinases (IKKs) in shear stress activation of NF-kappaB and to elucidate the upstream signaling mechanism that mediates IKK activation. Our results demonstrate that IKKs in ECs are activated by shear stress in a rapid and transient manner. This IKK activation is followed by IkappaB degradation and NF-kappaB translocation into the nucleus. Transfection of plasmids encoding catalytic inactive mutants of IKKs, i.e. hemagglutinin (HA)-IKKalpha(K44M) and HA-IKKbeta(K44A), inhibits shear stress-induced NF-kappaB translocation. In addition, constructs encoding antisense IKKs, i.e. HA-IKKalpha(AS) and HA-IKKbeta(AS), attenuate shear stress induction of a promoter driven by the kappaB enhancer element. Preincubation of the EC monolayer with a monoclonal anti-alphavbeta3 integrin antibody (clone LM609) attenuates shear stress induction of IKK. Inhibition of tyrosine kinases by genistein causes a similar down-regulating effect. These results suggest that the integrin-mediated signaling pathway regulates NF-kappaB through IKKs in ECs in response to shear stress.

Epidemiological identification of Chinese individuals putatively susceptible or insusceptible to Schistosoma japonicum: a prelude to immunogenetic study of human resistance to Asian schistosomiasis

An epidemiological method, field-tested in Hunan, China, to identify residents potentially susceptible or insusceptible to endemic schistosomiasis japonica is described, as a prelude to selection of subjects for immunogenetic studies. After an initial cross-sectional survey on two islands (Qingshan and Niangashan--population 2990) in 1995-1996, an informative cohort (N = 249) was selected for treatment and 9-month follow-up to measure exposure and re-infection. Both the population prevalence (15.8%) and the geometric mean intensity of infection (26.2 eggs/g faces) indicated that the islands were moderately endemic for schistosomiasis. Exposure measurements revealed a strong, positive, linear association (r = 0.70) between daily activity diaries and direct water-contact observation. Individuals identified as stool-positive for schistosomiasis had significantly more water contact than those who were egg-negative (P = 0.03). Almost all (93%) of the cohort had ultrasonographic evidence of periportal fibrosis before treatment but in only 1.2% was this fibrosis scored > 1 in terms of the stages identified by the World Health Organization. At the follow-up it was possible to classify the 249 subjects into three, distinct, exposure-infection epidemiological groups. The first group (N = 20) was susceptible to re-infection and constituted 8% of the cohort. The second group (N = 61) was apparently insusceptible to re-infection despite the continuing high levels of exposure and included 24% of the cohort. The other 68% of the cohort (N = 168) remained uninfected but were at most only moderately exposed, or had a status indeterminate due to non-compliance. This epidemiological identification of susceptibles and insusceptibles for schistosomiasis japonica' links field and ongoing laboratory studies aimed at characterising the genetic and immunological factors associated with resistance to re-infection and/or disease.

Ribonuclease E organizes the protein interactions in the Escherichia coli RNA degradosome

The Escherichia coli RNA degradosome is the prototype of a recently discovered family of multiprotein machines involved in the processing and degradation of RNA. The interactions between the various protein components of the RNA degradosome were investigated by Far Western blotting, the yeast two-hybrid assay, and coimmunopurification experiments. Our results demonstrate that the carboxy-terminal half (CTH) of ribonuclease E (RNase E) contains the binding sites for the three other major degradosomal components, the DEAD-box RNA helicase RhlB, enolase, and polynucleotide phosphorylase (PNPase). The CTH of RNase E acts as the scaffold of the complex upon which the other degradosomal components are assembled. Regions for oligomerization were detected in the amino-terminal and central regions of RNase E. Furthermore, polypeptides derived from the highly charged region of RNase E, containing the RhlB binding site, stimulate RhlB activity at least 15-fold, saturating at one polypeptide per RhlB molecule. A model for the regulation of the RhlB RNA helicase activity is presented. The description of RNase E now emerging is that of a remarkably complex multidomain protein containing an amino-terminal catalytic domain, a central RNA-binding domain, and carboxy-terminal binding sites for the other major components of the RNA degradosome.

Diagnosis of schistosomiasis japonica in Chinese schoolchildren by administration of a questionnaire

This paper describes a rapid, simple, cost-effective questionnaire for screening school-aged children at risk for Asian schistosomiasis in China. Five hundred and thirty-two children, aged 8-14 years, were selected from 3 schools in an area moderately endemic for Schistosoma japonicum in Hunan province. The questionnaire, comprising 15 multiple-choice questions, was administered by teachers in order to collect both ethnographic and epidemiological data relevant to current S. japonicum infections. This was followed by Kato-Katz thick smear stool examinations, miracidium hatching tests, and soluble egg antigen-enzyme linked immunosorbent assays in order to validate the efficacy of the questionnaire approach. The results from a combination of all 3 procedures indicated that the overall schistosomiasis prevalence in the 3 schools was 29.9% (138/472). Six risk factors (episodes of diarrhoea, frequency of water contact, school grade attained, weakness, past history of S. japonicum infection(s), and whether a subject had been previously treated for schistosomiasis) in the questionnaire were determined by logistic regression to be highly statistically significant predictors of individual current infection. The sensitivity (93.7%), specificity (91.9%) and low cost (c. US$ 0.6/true positive case) associated with the 6 variables model make the questionnaire approach a very useful diagnostic tool for screening marshland and lake communities at high risk for schistosomiasis in China before selective treatment with praziquantel or diagnostic follow-up. An even simpler 3 variables 'yes/no' model was derived from the questionnaire and found to be nearly as good at predicting individual infection (sensitivity 86.2% and specificity exceeding 97.6%) and extremely simple to use. If validated in other ecological settings in China the questionnaire, modified or as presented here, could be adopted by the national schistosomiasis control programme.

IFN-gamma induction of the human monocyte chemoattractant protein (hMCP)-1 gene in astrocytoma cells: functional interaction between an IFN-gamma-activated site and a GC-rich element

We characterized regulation of the human monocyte chemoattractant protein-1 (hMCP-1) gene by IFN-gamma in astrocytoma cells, because astroglial cells express chemokines in several central nervous system inflammatory states. It was found that IFN-gamma-induced hMCP-1 transcription was rapid, transient, and mediated by a 213-bp promoter-proximal regulatory region of the gene. Our studies on both in vitro and in vivo states of the hMCP-1 regulatory region established requirement of an IFN-gamma-activated site (GAS) and the presence of IFN-gamma-inducible GAS-binding activity involving at least STAT-1alpha for IFN-gamma-induced hMCP-1 expression. Unexpectedly, in vivo genomic footprinting of the proximal regulatory region of the IFN-gamma-induced gene revealed protection of a GC-rich sequence (GC box) with the same temporal pattern as that seen at the GAS; in vitro, this GC-rich element is associated with nuclear factor Sp1. These observations suggested a cooperative interaction between the GAS and the GC box element. Interestingly, site-specific mutations that abolished GC-box or GAS-element function produced clearly disparate results. Disruption of the GC box did not affect fold induction by IFN-gamma but reduced promoter-reporter expression by half. Conversely, GAS mutation abrogated induction but did not affect the magnitude of expression. These results establish the importance of the GAS element for induction of hMCP-1 and further our understanding of IFN-gamma-mediated transcriptional induction by providing the first evidence in vivo for inducible signaling to the GC box by this cytokine.

Differential antigen-stimulated proliferation of human mononuclear cells by recombinant Schistosoma japonicum antigens in a Chinese population

Peripheral blood mononuclear cells (PBMC) from 117 individuals living on two islands in an area (Dongting Lake) endemic for schistosomiasis japonica in China, and 15 control individuals from a non-endemic area of China, were assessed for antigen-stimulated proliferation against five recombinant Schistosoma japonicum antigens of recognized interest in the development of immunity to schistosomiasis. Two recombinant antigens, paramyosin and 28-kD glutathione-S-transferase, stimulated cellular proliferation (stimulation index > or = 3.0) in 38.5% and 42.5% of subjects, respectively, a level similar to that induced by a soluble whole parasite extract (51.3%). In contrast, three other recombinant antigens tested--a fatty acid binding protein, 22-kD tegumental membrane-associated antigen, and glyceraldehyde-3-phosphate dehydrogenase--stimulated PBMC proliferation in only 3-8% of subjects. Moreover, we also identified a positive association between the degree of exposure, and cellular proliferation following stimulation with recombinant paramyosin or whole parasite extract. Highly significant differences in antigen-stimulated proliferation were also observed between the two islands, Niangashan and Qingshan. The whole parasite extract stimulated proliferation in 90% of subjects from Niangashan island compared with only 42.1% of subjects from Qingshan island (chi2 = 16.88, P = 0.00004), while glutathione-S-transferase stimulated proliferation in 77.3% of subjects from Niangashan island compared with only 34.7% of subjects from Qingshan island (chi2 = 13.09, P = 0.003). A similar, but not significant, trend was observed for paramyosin and the fatty-acid binding protein. The identification of differential cellular proliferative responses to specific schistosome antigens within an infected human population may have important practical implications for vaccine development against schistosomiasis japonica.