Correlations of microRNA:microRNA expression patterns reveal insights into microRNA clusters and global microRNA expression patterns.

MicroiRNAs are genome encoded small double stranded RNAs that regulate expression of homologous mRNAs. With approximately 2500 human miRNAs and each having hundreds of potential mRNA targets, miRNA based gene regulation is quite pervasive in both development and disease. While there are numerous studies investigating miRNA:mRNA and miRNA:protein target expression correlations, there are relatively few studies of miRNA:miRNA co-expression. Here we report on our analysis of miRNA:miRNA co-expression using expression data from the miRNA expression atlas of Landgraf et al. Our analysis indicates that many, but not all, genomically clustered miRNAs are co-expressed as a single pri-miRNA transcript. We have also identified co-expression groups that have similar biological activity. Further, the non-correlative miRNAs we have uncovered have been shown to be of utility in establishing miRNA biomarkers and signatures for certain tumours and cancers.

Post-transcriptional gene silencing of ribosomal protein S6 kinase 1 restores insulin action in leucine-treated skeletal muscle.

Excessive nutrients, especially amino acids, impair insulin action on glucose metabolism in skeletal muscle. We tested the hypothesis that the branched-chain amino acid leucine reduces acute insulin action in primary myotubes via a negative feedback mechanism involving ribosomal protein S6 kinase 1 (S6K1). The effect of S6K1 on glucose metabolism was determined by applying RNA interference (siRNA). Leucine (5 mM) reduced glucose uptake and incorporation to glycogen by 13% and 22%, respectively, compared to the scramble siRNA-transfected control at the basal level. Leucine also reduced insulin-stimulated Akt phosphorylation, glucose uptake and glucose incorporation to glycogen (39%, 39% and 37%, respectively), and this reduction was restored after S6K1 silencing. Depletion of S6K1 enhanced basal glucose utilization and protected against the development of impaired insulin action, in response to excessive leucine. In conclusion, S6K1 plays an important role in the regulation of insulin action on glucose metabolism in skeletal muscle.

Characterization of signal transduction and glucose transport in skeletal muscle from type 2 diabetic patients.

We characterized metabolic and mitogenic signaling pathways in isolated skeletal muscle from well-matched type 2 diabetic and control subjects. Time course studies of the insulin receptor, insulin receptor substrate (IRS)-1/2, and phosphatidylinositol (PI) 3-kinase revealed that signal transduction through this pathway was engaged between 4 and 40 min. Insulin-stimulated (0.6-60 nmol/l) tyrosine phosphorylation of the insulin receptor beta-subunit, mitogen-activated protein (MAP) kinase phosphorylation, and glycogen synthase activity were not altered in type 2 diabetic subjects. In contrast, insulin-stimulated tyrosine phosphorylation of IRS-1 and anti-phosphotyrosine-associated PI 3-kinase activity were reduced 40-55% in type 2 diabetic subjects at high insulin concentrations (2.4 and 60 nmol/l, respectively). Impaired glucose transport activity was noted at all insulin concentrations (0.6-60 nmol/l). Aberrant protein expression cannot account for these insulin-signaling defects because expression of insulin receptor, IRS-1, IRS-2, MAP kinase, or glycogen synthase was similar between type 2 diabetic and control subjects. In skeletal muscle from type 2 diabetic subjects, IRS-1 phosphorylation, PI 3-kinase activity, and glucose transport activity were impaired, whereas insulin receptor tyrosine phosphorylation, MAP kinase phosphorylation, and glycogen synthase activity were normal. Impaired insulin signal transduction in skeletal muscle from type 2 diabetic patients may partly account for reduced insulin-stimulated glucose transport; however, additional defects are likely to play a role.

Effect of contraction on mitogen-activated protein kinase signal transduction in skeletal muscle. Involvement Of the mitogen- and stress-activated protein kinase 1.

Growing evidence suggests that activation of mitogen-activated protein kinase (MAPK) signal transduction mediates changes in muscle gene expression in response to exercise. Nevertheless, little is known about upstream or downstream regulation of MAPK in response to muscle contraction. Here we show that ex vivo muscle contraction stimulates extracellular signal-regulated kinase 1 and 2 (ERK1/2), and p38(MAPK) phosphorylation. Phosphorylation of ERK1/2 or p38(MAPK) was unaffected by protein kinase C inhibition (GF109203X), suggesting that protein kinase C is not involved in mediating contraction-induced MAPK signaling. Contraction-stimulated phosphorylation of ERK1/2 and p38(MAPK) was completely inhibited by pretreatment with PD98059 (MAPK kinase inhibitor) and SB203580 (p38(MAPK) inhibitor), respectively. Muscle contraction also activated MAPK downstream targets p90 ribosomal S6 kinase (p90(Rsk)), MAPK-activated protein kinase 2 (MAPKAP-K2), and mitogen- and stress-activated protein kinase 1 (MSK1). Use of PD98059 or SB203580 revealed that stimulation of p90(Rsk) and MAPKAP-K2 most closely reflects ERK and p38(MAPK) stimulation, respectively. Stimulation of MSK1 in contracting skeletal muscle required the activation of both ERK and p38(MAPK). These data demonstrate that muscle contraction, separate from systemic influence, activates MAPK signaling. Furthermore, we are the first to show that contractile activity stimulates MAPKAP-K2 and MSK1.

Postexercise glucose uptake and glycogen synthesis in skeletal muscle from GLUT4-deficient mice.

To determine the role of GLUT4 on postexercise glucose transport and glycogen resynthesis in skeletal muscle, GLUT4-deficient and wild-type mice were studied after a 3 h swim exercise. In wild-type mice, insulin and swimming each increased 2-deoxyglucose uptake by twofold in extensor digitorum longus muscle. In contrast, insulin did not increase 2-deoxyglucose glucose uptake in muscle from GLUT4-null mice. Swimming increased glucose transport twofold in muscle from fed GLUT4-null mice, with no effect noted in fasted GLUT4-null mice. This exercise-associated 2-deoxyglucose glucose uptake was not accompanied by increased cell surface GLUT1 content. Glucose transport in GLUT4-null muscle was increased 1.6-fold over basal levels after electrical stimulation. Contraction-induced glucose transport activity was fourfold greater in wild-type vs. GLUT4-null muscle. Glycogen content in gastrocnemius muscle was similar between wild-type and GLUT4-null mice and was reduced approximately 50% after exercise. After 5 h carbohydrate refeeding, muscle glycogen content was fully restored in wild-type, with no change in GLUT4-null mice. After 24 h carbohydrate refeeding, muscle glycogen in GLUT4-null mice was restored to fed levels. In conclusion, GLUT4 is the major transporter responsible for exercise-induced glucose transport. Also, postexercise glycogen resynthesis in muscle was greatly delayed; unlike wild-type mice, glycogen supercompensation was not found. GLUT4 it is not essential for glycogen repletion since muscle glycogen levels in previously exercised GLUT4-null mice were totally restored after 24 h carbohydrate refeeding.-Ryder, J. W., Kawano, Y., Galuska, D., Fahlman, R., Wallberg-Henriksson, H., Charron, M. J., Zierath, J. R. Postexercise glucose uptake and glycogen synthesis in skeletal muscle from GLUT4-deficient mice.

Cation-regulated self-association of "synapsable" DNA duplexes.

The simple innovation of introducing a block of G.G mismatches into a Watson-Crick DNA duplex permits two such duplexes, under conditions of physiological temperature and salt, to "synapse" with one another at their G.G mismatch sites via guanine-quartet formation. The short quadruplex formed at the "synapsed" site necessarily has its strands in an antiparallel, or partially antiparallel orientation. We wished to test whether a different, and more stable, synapsis might be achieved if one of the two strands in the synapsable duplex had its domain of guanine residues in a reverse orientation to the rest of the strand, via 5'-5' and 3'-3' linkages. Such modified duplexes might synapse via the formation of the thermodynamically preferred parallel quadruplex. Our results indicate that such "parallel" and "antiparallel" synaptic events have dramatically different requirements for cations. We use chemical probing experiments to provide evidence for a kinetic model for this discrepancy. It may be possible to exploit the distinct properties of the above two kinds of synapsable duplexes for a variety of in vivo and in vitro applications.

Co-operation between Canada and other countries and territories to promote countermeasures against illicit drug trafficking.

This article reviews the current programme and legislation relating to drug control and co-operation in drug law enforcement between Canada and other countries. The article also outlines the measures proposed by the authors to promote world-wide co-operation in controlling the illicit traffic in drugs. The authors make the following suggestions: in order to prevent individuals involved in organized crime from profiting from their illegal activities, standards for criminal laws should be established at the international level to ensure that no country or territory can be used as a haven for organized crime and profits derived from it; national Governments must ensure that co-operation is extended to all investigations and enquiries concerning organized crime; bilateral and multilateral treaties should be developed and adopted to ensure the exchange of information and mutual co-operation in law enforcement action against organized crime; international co-operation is needed to ensure the effective prosecution of individuals involved in organized international criminal groups and the removal of their illegally accumulated profits, which should result in the dismantling of the illegal organizations to prevent their entrenchment in contemporary societies.

Illicit traffic and abuse of cannabis in Canada.

In 1984 cannabis derivatives, in particular marijuana, hashish and liquid hashish, continued to be the most readily available drugs of abuse in Canada. Marijuana originating in Colombia decreased on the illicit marijuana market in Canada from an estimated 45 per cent in 1983 to 30 per cent in 1984, but it remained the largest source of marijuana supply. Marijuana originating in Thailand remained at approximately the same level (20 per cent) in 1984 as in 1983, while marijuana of Jamaican origin increased its share in the illicit market from 10 per cent in 1983 to 20 per cent in 1984. Approximately 10 per cent of marijuana on the illicit market originated in Canada, 10 per cent in Mexico, and 10 per cent in the United States of America. In 1984 an estimated 85 per cent of hashish on the illicit market in Canada originated in Lebanon (55 per cent in 1983), 10 per cent in India or Pakistan (31 per cent in 1983) and 5 per cent in Jamaica (2 per cent in 1983). Illicit shipments in tonnes of hashish originating in Lebanon made this the dominant source of supply of the drug. Liquid hashish originating in Jamaica shared 88 per cent of the illicit market of this drug in Canada during 1984, while 10 per cent of the drug originated in Lebanon and 2 per cent in Canada. In 1984 an estimated 40 per cent of smuggled marijuana entered the illicit market in Canada by air and approximately the same amount by sea, while 20 per cent was smuggled over land. During the same year, hashish was smuggled into Canada primarily by sea, while air accounted for 5 per cent and land for 1 per cent only. Liquid hashish, in contrast, entered Canada primarily by air, and only 9 per cent by land and 1 per cent by sea.

Illicit traffic and abuse of cannabis in Canada

In 1984 cannabis derivatives, in particular marijuana, hashish and liquid hashish, continued to be the most readily available drugs of abuse in Canada. Marijuana originating in Colombia decreased on the illicit marijuana market in Canada from an estimated 45 percent in 1983 to 30 percent in 1984, but it remained the largest source of marijuana supply. Marijuana originating in Thialand remained at approximately the same level (20 percent) in 1984 as in 1983, while marijuana of Jamaican origin increased its share in the illicit market from 10 percent in 1983 to 20 percent in 1984. Approximately 10 percent of marijuana on the illicit market originated in Canada, 10 percent in Mexico, and 10 per cent in the United States of America. In 1984 an estimated 85 percent of hashish on the illicit market in Canada originated in Lebanon (55 percent in 1983), 10 percent in India or Pakistan (31 percent in 1983) and 5 percent in Jamaica (2 percent in 1983). Illicit shipments in tonnes of hashish originating in Lebanon made this the dominant source of supply of the drug. Liquid hashish originating in Jamaica shared 88 percent of the illicit market of this drug in Canada during 1984, while 10 percent of the drug originated in Lebanon and 2 percent in Canada. In 1984 an estimated 40 percent of smuggled marijuana entered the illicit market in Canada by air and approximately the same by sea, while 20 percent was smuggled over land. During the same year, hashish was smuggled into Canada primarily by sea, while air accounted for 5 percent and land for 1 per cent only. Liquid hashish, in contrast, entered Canada primarily by air, and only 9 percent by land and 1 percent by sea (AU)

Illicit traffic and abuse of cocaine.

There has been an increasing availability and abuse of cocaine in Canada in recent years. Cocaine abuse has spread from the affluent adult sectors of society to middle-income groups and the young, involving large sections of the population. The increase in illicit demand for, and the social acceptability of, cocaine has led to an increase in illicit cocaine supply. The availability of cocaine on the illicit market has been sustained by a vast over-production of the raw materials needed to produce cocaine in coca-growing areas of South America and the activities of sophisticated trafficking organizations with large operations and profits. As a result, cocaine prices at the wholesale level in South America and Canada are declining, and at the retail level in Canada have remained relatively stable or have slightly decreased. It has been estimated that more than one half of the amount of cocaine on the illicit market in Canada was illegally produced in Colombia, but the main quantities of the raw materials used for such production originated in Bolivia and Peru. Cocaine is smuggled into Canada primarily by commercial air transport, arriving at the three principal ports of entry, namely Montreal, Toronto and Vancouver, from whence it is distributed to other parts of the country. As drug law enforcement efforts increase in one area, traffickers shift their illicit operations to other areas in an attempt to escape detection. Current evidence suggests that both the availability and abuse of cocaine in Canada are likely to increase in the coming years.

Recent trends in illicit drug trafficking from the Canadian perspective.

Parts of south-west Asia where opium is illicitly produced have recently become the principal source of supply of heroin to Canada, accounting for 79 per cent of this drug on the illicit market. Heroin from parts of south-east Asia is expected, however, to regain a greater share of the market in the next few years. That may result in increased availability of heroin in Canada. The availability of cocaine has increased on the illicit market; some 57 per cent of this drug originated in Colombia in 1982. Cocaine is increasingly abused in Canada by an estimated 250,000 persons, and this trend seems likely to continue in the next few years. Cannabis plant, cannabis resin and liquid cannabis are the most readily available and widely abused illicit drugs. An illicit demand has been created for the more potent preparations of cannabis. The dramatic increase in armed robberies perpetrated by criminal groups to procure manufactured drugs is a relatively new and alarming trend. The illicit drug market in Canada is largely controlled by organized criminal syndicates.

The profits of organized crime: the illicit drug trade in Canada.

Massive funds that are produced from street-level crime are laundered upwards into the criminal organizations for the benefit of their top-level members. The laundering systems used to distribute the proceeds of crime are designed to conceal the size of the organization as well as the identity of its members. Crime syndicates are attracted to criminal activity that produces the highest profits with the lowest risks. Although organized crime syndicates derive profits from a wide variety of criminal activity, their most sought after ventures principally involve the consensual type of crimes, such as drug trafficking, where no one individual can be readily identified as a legal victim for the purpose of recovering the proceeds of a criminal act. A recent survey indicated that illicit drug trafficking accounted for 87 per cent of the cash flow generated from organized crime. When the proceeds are disbursed, the criminals are free of the usual civil liability respecting the ownership of the proceeds. Canada currently has several laws which enhance the ability of law-enforcement authorities to trace the proceeds of crime and prosecute those who possess the assets. This legislation has some limitations with respect to seizure and forfeiture of certain types of proceeds. For example, forfeiture of the illegally acquired property is difficult when there is no original legal owner to initiate legal action, and even more difficult if the assets are located abroad.