Reconstructing axial progenitor field dynamics in mouse stem cell-derived embryoids

Embryogenesis requires substantial coordination to translate genetic programs to the collective behavior of differentiating cells, but understanding how cellular decisions control tissue morphology remains conceptually and technically challenging. Here, we combine continuous Cas9-based molecular recording with a mouse embryonic stem cell-based model of the embryonic trunk to build single-cell phylogenies that describe the behavior of transient, multipotent neuro-mesodermal progenitors (NMPs) as they commit into neural and somitic cell types. We find that NMPs show subtle transcriptional signatures related to their recent differentiation and contribute to downstream lineages through a surprisingly broad distribution of individual fate outcomes. Although decision-making can be heavily influenced by environmental cues to induce morphological phenotypes, axial progenitors intrinsically mature over developmental time to favor the neural lineage. Using these data, we present an experimental and analytical framework for exploring the non-homeostatic dynamics of transient progenitor populations as they shape complex tissues during critical developmental windows.

Improving prime editing with an endogenous small RNA-binding protein

Prime editing enables the precise modification of genomes through reverse transcription of template sequences appended to the 3' ends of CRISPR-Cas guide RNAs1. To identify cellular determinants of prime editing, we developed scalable prime editing reporters and performed genome-scale CRISPR-interference screens. From these screens, a single factor emerged as the strongest mediator of prime editing: the small RNA-binding exonuclease protection factor La. Further investigation revealed that La promotes prime editing across approaches (PE2, PE3, PE4 and PE5), edit types (substitutions, insertions and deletions), endogenous loci and cell types but has no consistent effect on genome-editing approaches that rely on standard, unextended guide RNAs. Previous work has shown that La binds polyuridine tracts at the 3' ends of RNA polymerase III transcripts2. We found that La functionally interacts with the 3' ends of polyuridylated prime editing guide RNAs (pegRNAs). Guided by these results, we developed a prime editor protein (PE7) fused to the RNA-binding, N-terminal domain of La. This editor improved prime editing with expressed pegRNAs and engineered pegRNAs (epegRNAs), as well as with synthetic pegRNAs optimized for La binding. Together, our results provide key insights into how prime editing components interact with the cellular environment and suggest general strategies for stabilizing exogenous small RNAs therein.

Recording morphogen signals reveals origins of gastruloid symmetry breaking

When cultured in three dimensional spheroids, mammalian stem cells can reproducibly self-organize a single anterior-posterior axis and sequentially differentiate into structures resembling the primitive streak and tailbud. Whereas the embryo's body axes are instructed by spatially patterned extra-embryonic cues, it is unknown how these stem cell gastruloids break symmetry to reproducibly define a single anterior-posterior (A-P) axis. Here, we use synthetic gene circuits to trace how early intracellular signals predict cells' future anterior-posterior position in the gastruloid. We show that Wnt signaling evolves from a homogeneous state to a polarized state, and identify a critical 6-hour time period when single-cell Wnt activity predicts future cellular position, prior to the appearance of polarized signaling patterns or morphology. Single-cell RNA sequencing and live-imaging reveal that early Wnt-high and Wnt-low cells contribute to distinct cell types and suggest that axial symmetry breaking is driven by sorting rearrangements involving differential cell adhesion. We further extend our approach to other canonical embryonic signaling pathways, revealing that even earlier heterogeneity in TGFβ signaling predicts A-P position and modulates Wnt signaling during the critical time period. Our study reveals a sequence of dynamic cellular processes that transform a uniform cell aggregate into a polarized structure and demonstrates that a morphological axis can emerge out of signaling heterogeneity and cell movements even in the absence of exogenous patterning cues.

A multifaceted signal recorder of cellular experiences using Cas12a base-editing

Technological advances have led to the emergence of lineage tracers, but signal recorders for mammalian systems have remained elusive. Kempton et al. have developed a Cas12a base-editing signal recorder capable of capturing diverse signals and operating in various experimental designs. The recorder enables new opportunities to chronicle cellular history.

Lineage tracing reveals the phylodynamics, plasticity, and paths of tumor evolution

Tumor evolution is driven by the progressive acquisition of genetic and epigenetic alterations that enable uncontrolled growth and expansion to neighboring and distal tissues. The study of phylogenetic relationships between cancer cells provides key insights into these processes. Here, we introduced an evolving lineage-tracing system with a single-cell RNA-seq readout into a mouse model of Kras;Trp53(KP)-driven lung adenocarcinoma and tracked tumor evolution from single-transformed cells to metastatic tumors at unprecedented resolution. We found that the loss of the initial, stable alveolar-type2-like state was accompanied by a transient increase in plasticity. This was followed by the adoption of distinct transcriptional programs that enable rapid expansion and, ultimately, clonal sweep of stable subclones capable of metastasizing. Finally, tumors develop through stereotypical evolutionary trajectories, and perturbing additional tumor suppressors accelerates progression by creating novel trajectories. Our study elucidates the hierarchical nature of tumor evolution and, more broadly, enables in-depth studies of tumor progression.

Single-cell lineages reveal the rates, routes, and drivers of metastasis in cancer xenografts

Detailed phylogenies of tumor populations can recount the history and chronology of critical events during cancer progression, such as metastatic dissemination. We applied a Cas9-based, single-cell lineage tracer to study the rates, routes, and drivers of metastasis in a lung cancer xenograft mouse model. We report deeply resolved phylogenies for tens of thousands of cancer cells traced over months of growth and dissemination. This revealed stark heterogeneity in metastatic capacity, arising from preexisting and heritable differences in gene expression. We demonstrate that these identified genes can drive invasiveness and uncovered an unanticipated suppressive role for KRT17 We also show that metastases disseminated via multidirectional tissue routes and complex seeding topologies. Overall, we demonstrate the power of tracing cancer progression at subclonal resolution and vast scale.

Inference of single-cell phylogenies from lineage tracing data using Cassiopeia

The pairing of CRISPR/Cas9-based gene editing with massively parallel single-cell readouts now enables large-scale lineage tracing. However, the rapid growth in complexity of data from these assays has outpaced our ability to accurately infer phylogenetic relationships. First, we introduce Cassiopeia-a suite of scalable maximum parsimony approaches for tree reconstruction. Second, we provide a simulation framework for evaluating algorithms and exploring lineage tracer design principles. Finally, we generate the most complex experimental lineage tracing dataset to date, 34,557 human cells continuously traced over 15 generations, and use it for benchmarking phylogenetic inference approaches. We show that Cassiopeia outperforms traditional methods by several metrics and under a wide variety of parameter regimes, and provide insight into the principles for the design of improved Cas9-enabled recorders. Together, these should broadly enable large-scale mammalian lineage tracing efforts. Cassiopeia and its benchmarking resources are publicly available at www.github.com/YosefLab/Cassiopeia.

Molecular recording of mammalian embryogenesis

Ontogeny describes the emergence of complex multicellular organisms from single totipotent cells. This field is particularly challenging in mammals, owing to the indeterminate relationship between self-renewal and differentiation, variation in progenitor field sizes, and internal gestation in these animals. Here we present a flexible, high-information, multi-channel molecular recorder with a single-cell readout and apply it as an evolving lineage tracer to assemble mouse cell-fate maps from fertilization through gastrulation. By combining lineage information with single-cell RNA sequencing profiles, we recapitulate canonical developmental relationships between different tissue types and reveal the nearly complete transcriptional convergence of endodermal cells of extra-embryonic and embryonic origins. Finally, we apply our cell-fate maps to estimate the number of embryonic progenitor cells and their degree of asymmetric partitioning during specification. Our approach enables massively parallel, high-resolution recording of lineage and other information in mammalian systems, which will facilitate the construction of a quantitative framework for understanding developmental processes.

Mouse ooplasm confers context-specific reprogramming capacity

Enucleated oocytes have the distinctive ability to reprogram somatic nuclei back to totipotency. Here, we investigate genome-scale DNA methylation patterns after nuclear transfer and compare them to the dynamics at fertilization. We identify specific targets for DNA demethylation after nuclear transfer, such as germline-associated promoters, as well as unique limitations that include certain repetitive element classes.

Epigenomics and chromatin dynamics

A report of the 'Joint Keystone Symposium on Epigenomics and Chromatin Dynamics', Keystone, Colorado, 17-22 January 2012.

This year's Joint Keystone Symposium on Epigenomics and Chromatin Dynamics was one of the largest Keystone meetings to date, reflecting the excitement and many developments in this area. Richard Young opened the meeting by giving a historic overview before sharing more detailed insights from his recent work in describing the role of the lysine demethylase Lsd1 in mouse embryonic stem (ES) cell differentiation. He also set the broader stage and highlighted the excitement concerning recent advances in epigenetic drugs such as the new bromodomain inhibitors.

Assessment of metagenomic assembly using simulated next generation sequencing data

Due to the complexity of the protocols and a limited knowledge of the nature of microbial communities, simulating metagenomic sequences plays an important role in testing the performance of existing tools and data analysis methods with metagenomic data. We developed metagenomic read simulators with platform-specific (Sanger, pyrosequencing, Illumina) base-error models, and simulated metagenomes of differing community complexities. We first evaluated the effect of rigorous quality control on Illumina data. Although quality filtering removed a large proportion of the data, it greatly improved the accuracy and contig lengths of resulting assemblies. We then compared the quality-trimmed Illumina assemblies to those from Sanger and pyrosequencing. For the simple community (10 genomes) all sequencing technologies assembled a similar amount and accurately represented the expected functional composition. For the more complex community (100 genomes) Illumina produced the best assemblies and more correctly resembled the expected functional composition. For the most complex community (400 genomes) there was very little assembly of reads from any sequencing technology. However, due to the longer read length the Sanger reads still represented the overall functional composition reasonably well. We further examined the effect of scaffolding of contigs using paired-end Illumina reads. It dramatically increased contig lengths of the simple community and yielded minor improvements to the more complex communities. Although the increase in contig length was accompanied by increased chimericity, it resulted in more complete genes and a better characterization of the functional repertoire. The metagenomic simulators developed for this research are freely available.

Long-acting beta2-agonists for poorly reversible chronic obstructive pulmonary disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is characterised by partially reversible airflow limitation. Many patients have little reversibility to short acting bronchodilators, but long acting bronchodilators are frequently advocated.

OBJECTIVES

To determine the effectiveness of long acting beta-2 adrenoceptor agonists (LABAs) in COPD patients demonstrating poor reversibility to short-acting bronchodilators.

SEARCH STRATEGY

The Cochrane Airways Group Specialised Register was searched ('all years' to 2005) along with the reference lists from identified randomised controlled trials (RCTs).

SELECTION CRITERIA

All RCTs comparing inhaled LABAs (salmeterol or formoterol) with placebo in the treatment of patients with stable, poorly reversible COPD. Studies were a minimum of four weeks in duration.

DATA COLLECTION AND ANALYSIS

Two authors independently performed data extraction and study quality assessment. If we required additional data, we contacted authors and pharmaceutical companies sponsoring the identified RCTs.

MAIN RESULTS

Twenty-three published and unpublished studies (6061 participants) were included in the review. There was a significant change in forced expiratory volume in 1 second (FEV1) in favour of salmeterol 50 mcg twice daily (BID) of 51 mls (95% confidence intervals (CI) 32 to 70), end of study morning peak expiratory flow (PEF) 14.89 L/min (95% CI 10.86 to 18.91). Supplemental short-acting bronchodilator usage was reduced by just under one puff per day. There were significant differences in the total, activity and impact domain scores of the St George's respiratory questionnaire in favour of salmeterol 50 mcg BID. Findings from other health status measurements and symptom scores were conflicting. There was no significant difference in exercise tolerance. The number of participants experiencing exacerbations was significantly reduced with salmeterol 50 mcg treatment compared with placebo (numbers needed to treat to benefit 21).

AUTHORS' CONCLUSIONS

This review shows that the treatment of patients with COPD with salmeterol 50 mcg produces modest increases in lung function. There were varying effects for other important outcomes such as health related quality of life or reduction in symptoms. However, there was a consistent reduction in exacerbations which may help people with COPD who suffer frequent deterioration of symptoms prompting healthcare utilisation. The strength of evidence for the use of salmeterol 100 mcg, formoterol 12 mcg, 18 mcg, 24 mcg was insufficient to provide clear indications for practice.

Synergy between ethanol and grape polyphenols, quercetin, and resveratrol, in the inhibition of the inducible nitric oxide synthase pathway

In atherosclerosis and tumor initiation, inducible nitric oxide synthase (iNOS) has been implicated in the damage of vascular walls and DNA, respectively. Moderate consumption of red wine has been ascribed as a preventive for coronary heart disease; however, there has been much debate over whether the beneficial effect is from grape polyphenolic components or ethanol. We studied the interaction of grape compounds on nitric oxide (NO) production by macrophages, mediators of blood vessel damage in atherosclerosis. For the murine macrophage cell line RAW 264.7, stimulation with lipopolysaccharide and interferon-gamma led to expression of the iNOS gene and production of NO. The polyphenols quercetin and resveratrol at a micromolar range suppressed iNOS gene expression and NO production, as determined by reverse transcription-polymerase chain reaction and nitrite assay. The polyphenols were also found to be scavengers of NO in an acellular system using sodium nitroprusside under physiological conditions. Ethanol, at a moderate level, did not produce any appreciable level of reduction of iNOS or NO activity. However, its presence at 0.1 to 0.75% enhanced the effect of grape polyphenols concentration-dependently. Thus, the interaction between these components plays a significant role in the health effects of red wine, especially with respect to their effect on the NO pathway.

A PCR-ELISA Method for Direct Detection of the Oyster Pathogen Haplosporidium nelsoni

: A rapid method, utilizing both polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA), was developed for detection of oyster MSX disease. The technique included using Haplosporidium nelsoni pathogen-specific PCR primers (based on ribosomal RNA genes), a Chelex resin (for rapid DNA extraction from oyster mantle tissues), and cloned H. nelsoni rRNA plasmid DNA (for use as a capture probe). Digoxigenin was incorporated into the pathogen-specific PCR products, which were captured by the coated probe in a fast hybridization reaction and then detected by ELISA. The sensitivity of PCR amplification on cloned plasmid DNA was 10 fg for detection by stained agarose gel, and increased to 0.01 fg for ELISA. Positive signals were observed in infected oysters using the PCR-ELISA technique. This method may be applicable to early detection of infection.

In vivo inhibition of nitric oxide synthase gene expression by curcumin, a cancer preventive natural product with anti-inflammatory properties

Curcumin is a naturally occurring, dietary polyphenolic phytochemical that is under preclinical trial evaluation for cancer preventive drug development and whose working pharmacological actions include anti-inflammation. With respect to inflammation, in vitro, it inhibits the activation of free radical-activated transcription factors, such as nuclear factor kappaB (NFkappaB) and AP-1, and reduces the production of pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF alpha), interleukin-1beta (IL-1beta), and interleukin-8. Inducible nitric oxide synthase (iNOS) is an inflammation-induced enzyme that catalyzes the production of nitric oxide (NO), a molecule that may lead to carcinogenesis. Here, we report that in ex vivo cultured BALB/c mouse peritoneal macrophages, 1-20 microM of curcumin reduced the production of iNOS mRNA in a concentration-dependent manner. Furthermore, we demonstrated that, in vivo, two oral treatments of 0.5 mL of a 10-microM solution of curcumin (92 ng/g of body weight) reduced iNOS mRNA expression in the livers of lipopolysaccharide(LPS)-injected mice by 50-70%. Although many hold that curcumin needs to be given at dosages that are unattainable through diet to produce an in vivo effect, we were able to obtain potency at nanomoles per gram of body weight. This efficacy is associated with two modifications in our preparation and feeding regimen: 1) an aqueous solution of curcumin was prepared by initially dissolving the compound in 0.5 N NaOH and then immediately diluting it in PBS; and 2) mice were fed curcumin at dusk after fasting. Inhibition was not observed in mice that were fed ad lib., suggesting that food intake may interfere with the absorption of curcumin.

Inhibition of inducible nitric oxide synthase gene expression and enzyme activity by epigallocatechin gallate, a natural product from green tea

Chronic inflammation has been implicated as the underlying factor in the pathogenesis of many disorders. In the past decade, inflammation-related endogenous production of reactive nitrogen species, similar to oxygen free radicals, has also been suggested as a risk factor for cancer, in addition to the well-studied exogenous nitroso compounds. Epidemiological, in vitro, and animal model studies have implicated green tea to be protective against nitroso compound-induced and inflammation-related cancer. Therefore, we investigated the effect of epigallocatechin-3-gallate (EGCG), one of the known biologically active catechins contained in green tea, on the production of nitric oxide (NO.). We have shown previously that EGCG reduces NO. production as measured by nitrite accumulation in the culture medium. Expanding on this finding, in this report we show that EGCG may do so by two mechanisms: reduction of inducible nitric oxide synthase (iNOS) gene expression and inhibition of enzyme activity. Addition of 1-10 microM EGCG to lipopolysaccharide- and interferon-gamma-activated mouse peritoneal cells reduced iNOS mRNA expression concentration dependently, to 82-14%, as measured by relative reverse transcription-polymerase chain reaction. Addition of 50-750 microM EGCG, in a concentration-dependent manner, inhibited the enzyme activity of iNOS, to 85-14%, and neuronal nitric oxide synthase (nNOS), to 93-56%, as measured by citrulline formation. EGCG competitively inhibited binding of arginine and tetrahydrobiopterin, and the gallate structure is important for this action.

Effects of food restriction in military training on T-lymphocyte responses

In a stress model which included food restriction, we examined the effects of physically rigorous military training and increased caloric intake on T-lymphocyte responses and lymphocyte subsets. T-lymphocyte proliferation and release of soluble receptor for interleukin-2 (slL-2R) in vitro were measured in two separate training classes of male U.S. Army ranger course (RC) trainees at the start and during the RC. Trainees in group 1 (n = 55) and 2(n = 50), respectively, had mean (+/- SD) energy intakes of 11.8 +/- 7.0 and 13.6 +/- 6.7 MJ/d, averaged total daily energy expenditures of 16.7 and 17.6 MJ/d, and experienced body weight losses of 15.]% and 12.6%. Both groups showed decreases T-lymphocyte responses in vitro: proliferation to phytohemagglutinin (PHA) and tetanus toxoid (TT), and released slL-2R to PHA. Group 2 with an intended 15% increase in energy during the RC over group 1 showed 22% and 26% less severe suppressions of T-lymphocyte proliferation and released slL-2R, respectively, in vitro. Group 2 also showed that short-term (9 days) removal of the food restriction stressor allowed for corrected body weight, total lymphocyte and T-lymphocyte subset counts but not suppressed T-lymphocyte responses in vitro. These results demonstrate that soldiers in physically rigorous military training are at risk of suppressed T-lymphocyte immunocompetence, and this is greater if they also experience inadequate energy intake.

Impact of tamoxifen on peripubertal androgen imprinting of rat hepatic cytochrome P450 2C11, cytochrome P450 3A2, and steroid 5 alpha-reductase

Expression of sex-dependent rat hepatic cytochromes P450 and steroid 5 alpha-reductase is regulated mainly by the sex-specific pattern of growth hormone (GH) secretion and is subject to androgen imprinting. Since tamoxifen suppresses GH pulse amplitude and nadir levels, we investigated the effect of tamoxifen on peripubertal testosterone imprinting of hepatic CYP2C11, CYP3A2, CYP2A1, and steroid 5 alpha-reductase. Prepubertal tamoxifen administration (5 mg once daily s.c. on days 28 and 29 of age) to non-ovariectomized female Sprague-Dawley rats did not affect hepatic microsomal CYP2C11-dependent testosterone 2 alpha-hydroxylase, CYP3A-mediated testosterone 6 beta-hydroxylase, CYP2A1-dependent testosterone 7 alpha-hydroxylase, or steroid 5 alpha-reductase activity in adult rats. Testosterone treatment (5 mumol/kg, s.c., once daily) of intact female rats during either puberty (days 35-49 of age) or adult life (days 69-77 of age) had no effect on these enzyme activities in adult (78-day-old) female rats, but the same treatment given during both of these periods induced the male-specific testosterone 2 alpha- and 6 beta-hydroxylase activities and suppressed the female-predominant testosterone 7 alpha-hydroxylase and steroid 5 alpha-reductase activities, indicating that peripubertal testosterone administration imprints the adult androgen responsiveness but not the basal levels of these enzyme activities in non-ovariectomized female rats. However, peripubertal androgen imprinting of the basal levels of testosterone 2 alpha-hydroxylase and steroid 5 alpha-reductase activities was observed in female rats administered tamoxifen prepubertally. Tamoxifen pretreatment also enhanced testosterone imprinting of the adult androgen responsiveness of testosterone 2 alpha- and 6 beta-hydroxylase and steroid 5 alpha-reductase activities. The enhanced testosterone hydroxylase activities were, however, not associated with an increase in microsomal NADPH-cytochrome P450 reductase activity, but were accompanied by elevated hepatic CYP2C11 and CYP3A2 protein levels. Overall, the present study indicates that prepubertal tamoxifen administration does not interfere with the normal sex differentiation of the gender-dependent hepatic cytochromes P450 and steroid 5 alpha-reductase, but this drug modulates peripubertal androgen imprinting of CYP2C11, CYP3A2, and steroid 5 alpha-reductase in adult female rats.

Effects of three dietary phytochemicals from tea, rosemary and turmeric on inflammation-induced nitrite production

In chronic inflammation, cytokines induce the production of nitric oxide (NO.) that is converted to DNA damaging and carcinogenic peroxynitrite and nitrite. The compounds epigallocatechin gallate (EGCG), carnosol, and curcumin are non-vitamin phytochemicals contained in commonly consumed dietary plants. They are known to be anti-inflammatory and cancer preventive. Therefore, we studied their effect on the generation of peroxynitrite radicals and nitrite. They inhibited lipopolysaccharide (LPS) and interferon-gamma (IFN gamma) induced nitrite production by mouse peritoneal cells by more than 50% at 2.5-10 microM. Cell viability assays verified that the inhibition was not due to general cellular toxicity.

Efficacy of the herbicide trifluralin against four P-glycoprotein-expressing strains of Leishmania

Drug resistance has emerged as a major obstacle to chemotherapy for many infectious diseases. Trifluralin, an antimicrotubule herbicide, is a new experimental drug for treatment of leishmaniasis. Here, we found that it was effective against two strains of Leishmania that express the multidrug-resistant genes ldmdr1 and lmpgpA and two strains that express proteins that are immunologically cross-reactive with mammalian P glycoproteins. These results suggest that trifluralin is not subject to counteractions of these multidrug resistance mechanisms of Leishmania species.

Inhibition of tumor necrosis factor by curcumin, a phytochemical

Curcumin, contained in the rhizome of the plant Curcuma longa Linn, is a naturally occurring phytochemical that has been used widely in India and Indonesia for the treatment of inflammation. The pleiotropic cytokine tumor necrosis factor-alpha (TNF) induces the production of interleukin-1 beta (IL-1), and, together, they play significant roles in many acute and chronic inflammatory diseases. They have been implicated in the pathogenesis of intracellular parasitic infections, atherosclerosis, AIDS and autoimmune disorders. This report shows that, in vitro, curcumin, at 5 microM, inhibited lipopolysaccharide (LPS)-induced production of TNF and IL-1 by a human monocytic macrophage cell line, Mono Mac 6. In addition, it demonstrates that curcumin, at the corresponding concentration, inhibited LPS-induced activation of nuclear factor kappa B and reduced the biological activity of TNF in L929 fibroblast lytic assay.

Paromomycin resistance in Leishmania tropica: lack of correlation with mutation in the small subunit ribosomal RNA gene

The aminoglycoside antibiotic paromomycin is a potentially useful anti-leishmanial chemotherapeutic agent. Resistance to this antibiotic was studied using Leishmania tropica. Promastigotes resistant to 210 micrograms/ml of paromomycin were selected by exposing them to gradual increments of this drug. Previous work in Escherichia coli, Tetrahymena, and yeast mitochondrial mutants has demonstrated mutations in the E. coli small subunit ribosomal RNA at the 1409:1491 basepair position, or equivalent positions in other organisms, resulting in basepair disruption. When the nucleotide sequence at both the DNA and RNA levels of the resistant L. tropica promastigotes cultured in the presence of paromomycin was compared with those of the drug-sensitive parent, there was no sequence change at the putative mutation site. Paromomycin resistance in L. tropica is apparently due to other mechanisms.

A comparison of three induction agents in paediatric anaesthesia--cardiovascular effects and recovery

We studied 30 children undergoing circumcision randomly allocated to receive either thiopentone 4 mg.kg-1, propofol 2.5 mg.kg-1 or midazolam 0.5 mg.kg-1 (n = 10) IV over 30 seconds at induction of anaesthesia. Blood pressure and pulse rate during the first 15 minutes of induction were recorded by a Finapres 2300e and a Cardiocap CM-104, and changes from preinduction baseline compared between the three induction agents and the two recording instruments. Postoperatively, blood levels of the induction agents were measured and recovery from anaesthesia was assessed by clinical criteria, mood and sedation scores and psychomotor performance. The Cardiocap data revealed no statistically significant haemodynamic differences between the three induction agents. Finapres data demonstrated that propofol caused a greater decrease in mean arterial pressure when compared to thiopentone at one minute (P = 0.01) and the MAP remained significantly lower than midazolam at five minutes (P = 0.02), illustrating an advantage of continuous over intermittent non-invasive blood pressure monitoring. The midazolam group took longer to identify themselves compared to both the propofol (P = 0.005) and the thiopentone groups (P = 0.02), but there was no difference in the groups in time to eye-opening. Psychomotor performance on awakening was significantly worse in the midazolam group compared to the propofol (P < 0.03) and thiopentone groups (P < 0.02). Most children had recovered to 80% of their best, practised, unmedicated, preoperative performance four hours after awakening, irrespective of the induction agent administered. Drug blood levels correlated weakly with both methods of psychomotor assessment (r > or = 0.6). Of the three induction agents, thiopentone caused the least haemodynamic perturbation on induction, and anaesthesia induced with midazolam caused the greatest psychomotor impairment on awakening. Within one hour patients in all drug groups were equally awake, co-operative and co-ordinated.

Plant microtubule inhibitors against trypanosomatids

Trypanosomatid protozoa are etiologic agents of several prevalent tropical diseases. Tubulins constitute 10% of the total proteins of these organisms. In addition, they are conserved within the Trypanosomatidae family but are different from that of the mammalian hosts. Since current chemotherapy has severe side effects, new compounds are urgently needed. The microtubular system provides a target for selective chemotherapy. Plant microtubule inhibitors, trifluralin and its analogues, inhibits Leishmania and Trypanosoma brucei, and Marion Chan and Dunne Fong here discuss the biosafety and potential for development of drug resistance to these compounds.

Structure-function analysis of antimicrotubule dinitroanilines against promastigotes of the parasitic protozoan Leishmania mexicana

Although leishmaniasis is a major tropical disease, the currently available drugs are toxic and inadequate. We show that the antimicrotubule herbicide trifluralin has antileishmania activity. The present study aimed at deducing the relationship between the structure of the molecule and its antiprotozoan activity. Nine dinitroanilines, all of which were analogs of trifluralin, were compared. We found that pendimethalin was 2.5-fold more potent than trifluralin, and the higher efficacy may be correlated with molecular structural features that increase the accessibility to one nitro group. This association was further supported by molecular modeling. Moreover, trifluralin samples from two sources differed in their activities by more than threefold, and gas column chromatography showed that impurities were present in the more potent sample.

Herbicides to curb human parasitic infections: in vitro and in vivo effects of trifluralin on the trypanosomatid protozoans

Leishmaniasis is a major tropical disease for which current chemotherapies, pentavalent antimonials, are inadequate and cause severe side effects. It has been reported that trifluralin, a microtubule-disrupting herbicide, is inhibitory to Leishmania amazonensis. In this study, the in vitro effect of trifluralin on different species of trypanosomatid protozoans was determined. In addition to L. amazonensis, trifluralin is effective against Leishmania major and Leishmania tropica, which cause cutaneous infections, Leishmania donovani, which causes visceral disease, Leishmania panamensis, which may cause mucocutaneous infection, and Trypanosoma brucei, an important human and veterinary pathogen. Moreover, most encouragingly, trifluralin is effective in vivo as a topical ointment against L. major and Leishmania mexicana murine cutaneous leishmaniasis. Thus, trifluralin is a promising lead drug for several related, prevalent tropical diseases: leishmaniasis, trypanosomiasis of animals, and, possibly, African trypanosomiasis in humans.

T cell response in murine Leishmania mexicana amazonensis infection: production of interferon-gamma by CD8+ cells

The immune response to Leishmania major has been the subject of many investigations. However, Leishmania includes many species with different clinical manifestations. In this report, we studied the T cell response to L. mexicana amazonensis, a New World species, in a murine model. We found that, similar to L. major, an Old World species, resistant C57BL/6 mice produced a high level of IFN-gamma and a low level of IL-4. Conversely, susceptible BALB/c mice produced a much lower level of IFN-gamma and higher level of IL-4. Although IFN-gamma is one of the important lymphokines that mediate macrophage activation and thus the destruction of the intracellular parasites, which lymphocyte subsets are producing the IFN-gamma is still a controversy. Much evidence including the isolation of protective, IFN-gamma-producing, CD4+ cell lines have confirmed the participation of CD4+ Th1 cells unequivocally. However, both CD4+ and CD8+ cells produced IFN-gamma. Recently, an increasing body of evidence has appeared suggesting that CD8+ cells also play a role in the resolution of murine L. major infection. We found that in the L. m. amazonensis model, when CD8+ lymphocytes from resistant C57BL/6 mice were eliminated by anti-CD8 antibody and complement-mediated lysis, the IFN-gamma production was reduced by 77%. This indicated that CD8+ cells produced a significant amount of the IFN-gamma. However, our results also indicate that IFN-gamma production by CD8+ cells was dependent on CD4+ cells.

Analysis of the repertoire of human B-lymphocytes specific for type A and type B blood group terminal trisaccharide epitopes

Naturally occurring serum antibodies specific for the A and B blood group isoantigens are of great importance in medicine. By using A-type terminal trisaccharide (ATS) or B-type terminal trisaccharide (BTS) coupled to albumin as coating antigens, an enzyme-linked immunosorbent assay capable of detecting all ATS/BTS-binding antibodies was performed. The combination of this enzyme-linked immunosorbent assay with limiting-dilution methodology, using a polyclonal B-lymphocyte activator, permitted a monoclonal analysis of the human antibody repertoire that is specific for ATS and BTS in persons of different blood types. Most (78%) positive supernatants from type O cultures were monospecific for either ATS or BTS, and these were present at roughly equivalent frequencies. Nine supernatants with reactivity toward both ATS and BTS were tested by red cell adsorption; six had properties expected for true dually reactive monoclonal antibodies: adsorption with either A1 or B red cells eliminated both anti-ATS and anti-BTS activity. This finding accords with a monoclonal origin for anti-A,B. The analysis of cultures of peripheral blood lymphocytes from type A and B donors unexpectedly showed significant numbers of clones with apparent autospecificity. However, none of the anti-ATS-positive supernatants from type A cultures or anti-BTS-positive supernatants from type B cultures were adsorbable with A1 or B red cells, respectively. Consideration of only true (adsorbable) positives indicates that the type A and B anti-trisaccharide repertoires differ significantly from the type O repertoire, probably as a result of the action of normal self-tolerance mechanisms.

Confirmation of the human cathepsin B gene (CTSB) assignment to chromosome 8

Human cathepsin B gene (CTSB) has been mapped to two locations: 8p22 and 13q14. Here we confirm the chromosome 8 assignment by three independent methods: (1) analysis of human-hamster somatic cell hybrid DNA by polymerase chain reaction; (2) comparison of hybridization signals to cathepsin B in interphase nuclei of normal fibroblasts and fibroblasts with a chromosome 8 deletion; and (3) fluorescence in situ hybridization to metaphase spreads using cathepsin B cosmid clones. Our results indicate that human CTSB is located at 8p22-p23.1.

The neonatal immune response to washed and irradiated red cells: lack of evidence of lymphocyte activation

A total of 21 neonatal infants (11 males and 10 females) were evaluated for lymphocyte subpopulation changes and cellular activation following the receipt of washed and gamma-irradiated red cells. The mean donor exposure was 2 +/- 1.5 donors, and the mean white cell concentration of each 10-mL-per-kg transfusion was 2 x 10(7) cells. A total of 2800 rad (28 Gy) was delivered to each red cell unit prior to washing. The lymphocyte subsets CD3+, CD4+, CD8+, CD19+, CD3+/CD25+, CD3+/HLA-DR, CD4+/CD45RA, CD4+/CDw29, and CD4+/ICHL-1 were analyzed, as were plasma gamma-interferon and neopterin levels, before and after blood transfusion. Posttransfusion samples were obtained from 3 to 12 days after the last blood transfusion. There were no posttransfusion changes in the percentage of lymphocyte subsets analyzed. Furthermore, overlay-histogram analysis of pretransfusion and posttransfusion CD45RA-, CDw29-, and UCHL-1-positive helper T cells failed to reveal a shift in mean channel fluorescence intensity, which is indicative of a lack of cellular activation. Gamma-interferon levels remained unchanged after transfusion (range, 90 +/- 5.9 to 95.5 +/- 5.3 pg/mL), as did neopterin levels (range, 3.7 +/- 1.5 to 4.6 +/- 1.5 ng/mL). This study could not find any evidence, by either cellular or humoral markers, of the activation of neonatal lymphocytes by transfusion. It is hypothesized that this failure to observe lymphocyte activation is due to the low number of donor white cells present in washed, irradiated red cells and/or to a lack of recipient recognition of transfused, allogeneic, donor white cells.

Immune dysfunction in children after corrective surgery for congenital heart disease

OBJECTIVE

To study the effect of open- and closed-heart surgery on the immune status of infants and children.

DESIGN

Prospective study. Data collected before anesthesia and surgery and 2 and 24 hrs after surgery.

SETTING

Operating room and pediatric ICU in a children's hospital.

PATIENTS

Children undergoing surgery for correction of congenital heart disease (age 3 months to 12 yrs). A total of 31 patients were studied (open-heart surgery, n = 25; closed-heart surgery, n = 6).

MEASUREMENTS AND MAIN RESULTS

Increased neutrophil counts and lymphopenia were observed after both open- and closed-heart surgery. Serum levels of the complement components C3 and C4 were depressed after open-heart surgery, but not after closed procedures. The percentage of T3+ and T4+ lymphocytes, proliferative responses of the lymphocytes and serum immunoglobulin (Ig)G and IgM were decreased from preoperative levels after open-heart surgery. The percentage of T8+ lymphocytes and serum IgA levels did not change. Intraoperative variables and postoperative severity of illness (Pediatric Risk of Mortality score) did not correlate with immune suppression.

CONCLUSIONS

The immune system is affected after pediatric cardiac surgery, particularly after open-heart surgery.

Effects of consumption of caloric vs noncaloric sweet drinks on indices of hunger and food consumption in normal adults

This study examined the effects of aspartame, saccharin, and sucrose on hunger and food intake. Twenty normal adults consumed a standard breakfast followed 3 h later by 200 mL of either water or a sweetened drink. One hour later, subjects' ad libitum consumption of a standardized lunch was measured. Subjects recorded self-assessments of hunger-related indices every half hour on visual analogue scales (VAS). ANOVA with repeated measures showed a significant effect of drink type on VAS scores 15 and 45 min after drinks were consumed but not for other times or for lunch consumption. Hunger-related ratings after drink consumption were generally highest for water, lower for noncaloric sweeteners (NCSs), and lowest for sugar. Pairwise comparisons of means showed that only the ratings for sugar and water were significantly different. The results show that, under the conditions of this study, NCSs do not increase hunger or food intake.

A PstI DNA polymorphism in the human stefin A gene (STF 1)

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Correlation of cyclosporine and metabolite binding to cyclophilin and a 50 kDa binding protein with in vitro immunosuppression: a preliminary report

Seven purified cyclosporine (CsA) metabolites were analyzed for binding to cyclophilin and to a 50 kDa protein purified from a JURKAT cell line. In addition, the potency of the seven metabolites, relative to CsA, was obtained using a primary mixed lymphocyte culture (MLC) suppression assay. CsA, M1, 17, and 21 were found to be immunosuppressive in the concentration range used (0-500 ng/mL). These results were then compared to protein binding. CsA and metabolite 17 (M17) bound to both proteins. Conversely, M1, 13, 21, and 26 bound only to cyclophilin, while M8 and M18 bound only to the 50 kDa protein.

Effect of the anti-microtubule drug oryzalin on growth and differentiation of the parasitic protozoan Leishmania mexicana

The parasitic protozoan Leishmania mexicana differentiates from a non-motile intracellular amastigote in the mammalian macrophage phagolysosome into a motile, extracellular promastigote in the insect vector gut. This developmental program has been accomplished in vitro, thus providing a useful model for studying changes in the cytoskeleton during cell differentiation. The role of microtubules in leishmania differentiation was demonstrated by using the dinitroaniline herbicide oryzalin, which inhibited both leishmania proliferation and differentiation; 25 microM oryzalin reduced promastigote division by over 95%. Interestingly, at a sublethal dose (5 microM), promastigotes became round and multiflagellated but remained motile. At 50 microM oryzalin, the number of intracellular amastigotes decreased by 50%. However, leishmania differentiation seemed to be the most drug-sensitive stage: there was a 60% reduction in amastigote-to-promastigote differentiation at 0.5 microM oryzalin. The specific action of oryzalin on leishmania microtubules was verified by its inhibition of in vitro polymerization of leishmania microtubules, but not control mammalian microtubules (from rat brain). These findings indicate that microtubules play a major role in leishmania proliferation, maintenance of cell shape, and cytodifferentiation.

A preliminary study to evaluate an in vitro assay for determining patient whole blood immunosuppressive cyclosporine A and metabolite activity: comparison with cytosolic binding assays using cyclophilin or a 50-kilodalton binding protein, and the Abbott TDx cyclosporine A parent, and parent and metabolites assays

Thirty-five allograft recipients undergoing cyclosporine A (CsA) therapy were randomly selected to evaluate a "novel" in vitro assay that determines CsA and metabolite immunosuppressive activity in whole blood. The assay uses a third party mixed lymphocyte culture (MLC) system to which patient whole blood extracts containing CsA and metabolites are added. The ability of the extracted CsA and metabolites to inhibit proliferation in this system is proportional to the immune suppressive activity in whole blood. Comparison of the MLC suppression assay against Abbott TDx parent, TDx parent and metabolites, and radioreceptor assays utilizing cyclophilin or a 50-kDa binding protein isolated from JURKAT cytosol gave the following correlation coefficients: r = 0.612, r = 0.672, r = 0.362, and r = 0.775, respectively.

Beta 2-microglobulin and neopterin: predictive markers for human immunodeficiency virus type 1 infection in children?

The value of beta 2-microglobulin and neopterin concentrations in serum for early diagnosis of infants born to human immunodeficiency virus type 1 (HIV-1)-infected mothers was assessed. Concentrations of both markers were measured in serum samples from pediatric patients (Centers for Disease Control classifications P0, P1, and P2), as well as in age-matched normal subjects. Both beta 2-microglobulin and neopterin were significantly increased in HIV-1-infected symptomatic subjects (P2) compared to controls. Seventy-five percent of asymptomatic patients (P1) also had increased values. On the other hand, a significant overlap in concentrations of both markers in serum was found between controls and P0 patients. Thirty-eight percent of the P0 patients had values comparable to those of the P2 group. Persistently high concentrations of both markers in P0 patients may be indicative of HIV-1 infection.

Inhibition of leishmanias but not host macrophages by the antitubulin herbicide trifluralin

The dinitroaniline herbicide trifluralin (alpha, alpha, alpha-trifluoro-2,6-dinitro-N, N-dipropyl-p-toluidine), at micromolar concentrations, selectively inhibited both proliferation and differentiation of the parasitic protozoan Leishmania mexicana amazonensis. In vitro, radioactive trifluralin showed specific binding to leishmania tubulin but not to mammalian tubulin. Because herbicides such as trifluralin are economical and are considered safe for man and domesticated animals, they may serve as useful sources of potential antiparasitic agents.

Lack of association between slow acetylator status and spontaneous lupus erythematosus

The Chinese in Southeast Asia are recognized as a population group that has a relatively high prevalence of rapid "acetylators" and a relatively high incidence of systemic lupus erythematosus. This study was designed to evaluate the possibility that there were environmental lupus erythematosus provocative substances eliminated by acetylation that resulted in a preponderance of slow acetylators among patients with the disease. We compared acetylator status in 36 Chinese women with mild, stable, and confirmed lupus erythematosus and 36 healthy control subjects matched for age, sex, and ethnic origin. Acetylator status was determined by use of HPLC to assay 5-acetylamino-6-formylamino-3-methyluracil/methylxanthine (AFMU/MX) and AFMU/(AFMU + MX) ratios in urine 1 to 4 hours after drinking a strong cup of coffee (caffeine). By use of parametric and nonparametric methods of analysis, the frequency distribution of AFMU/MX and AFMU/(AFMU + MX) ratios in both the patients and control subjects were determined to be very similar. Thus there was no association between slow acetylator status and lupus erythematosus in the study subjects.

Bacterial expression of human cysteine proteinase inhibitor stefin A

Stefin A, a cysteine proteinase inhibitor of the cystatin superfamily, has been found to be most abundant in epidermal cells. In order to determine its cellular function, we have expressed human stefin A in Escherichia coli using plasmid expression vectors under the control of bacteriophage T7 RNA polymerase. The heat-stable, antibody-positive bacterial product was isolated using a papain-Sepharose affinity column and was shown to inhibit two cysteine proteinases, papain and human cathepsin B. Recombinant stefin A may have commercial and therapeutic potential in situations requiring inhibition of cysteine proteinase activities, and in cosmetics, as an ingredient in skin creams.

The Ly-10 antigen is a marker of mouse-activated T lymphocytes

Ly-10.1 is a lymphocyte surface antigen controlled by a gene linked to the Ly-1.1 locus and expressed on activated T helper, T suppressor (Ts), and cytotoxic T lymphocytes (CTL). In this report, we describe the following: 1) Ly-10 is a heterodimeric glycoprotein consisting of a 80,000 heavy and a 34,000 light chain. 2) Although mature CTL are Ly-10+ by negative selection with anti-Ly-10.1 and complement (C), CTL precursors reactive to allogeneic cells are Ly-10-. 3) Similarly, IL-2-producing effector T cells induced by Mls-incompatible cells and semiallogeneic stimulation are eliminated by anti-Ly-10.1 and C after activation but are not eliminated as precursors before activation. 4) In mixed lymphocyte culture with semiallogeneic cells, the frequency of Ly-10.1+ cells was highest on the 2nd to 5th day after stimulation, decreased by the 12th day, and increased after restimulation with fresh antigen as demonstrated by immunofluorescence, C-mediated lysis, and IL-2 production. 5) When spleen cells were treated with anti-Ly-10 and C before concanavalin A (Con A) activation, the suppressive activity in the Con A T blasts was reduced, suggesting that in normal mice, some Ts preexist in a Ly-10+ activated state. These results indicate that Ly-10 is a marker of activation of T cells, not expressed on precursor T cells and whose expression is both transient and dependent on the presence of antigen. The similarities in biochemical and cellular characteristics suggest that Ly-10 is a mouse homologue of the human lymphocyte activation marker 4F2.