Impact of tobacco flavoring on oral nicotine consumption in C57BL/6J mice

BACKGROUND

The continued use of flavors in tobacco products has been a prominent factor in their popularity, yet little is known regarding their role in nicotine dependence. This study aimed to investigate the impact of tobacco flavoring on oral nicotine consumption in mice using the two-bottle choice (2BC) test and assessed the potential impact of age and sex in their interactions.

METHODS

Adolescent and adult male and female C57BL/6J mice were used. First, voluntary consumption of tobacco flavor concentrate from a commercial electronic cigarette liquid vendor (Avail Vapor LLC) was measured; then, the effects of tobacco flavoring in combination with nicotine were examined. In one approach, tobacco flavor concentration was kept constant while nicotine concentration varied, and in the second, nicotine was kept constant while the tobacco flavor concentration varied.

RESULTS

Overall, tobacco flavoring decreased oral nicotine consumption in mice, and its effects were sex- and age-dependent. Although females consumed the tobacco-flavored solution at a slightly higher rate than males, male mice were more sensitive to the effects of the combination (nicotine + tobacco). Furthermore, adolescent mice showed a starker reduction in nicotine consumption in the presence of tobacco flavoring compared to adult mice. This attenuation was most likely due to a basal aversion to the tobacco flavoring itself, thus, creating a negative synergistic effect with nicotine.

CONCLUSIONS

Tobacco flavoring increases aversion to nicotine in the 2BC test in C57BL6J mice, suggesting that some flavors may diminish rather than enhance oral nicotine consumption in rodents.

Genotypic Differences in the Effects of Menthol on Nicotine Intake and Preference in Mice

Menthol has been shown to exacerbate elements of nicotine addiction in humans and rodents; however, the mechanisms mediating its effects are not fully understood. This study examined the impact of genetic factors in menthol’s effects on oral nicotine consumption by comparing two inbred mouse strains with differing sensitivities to nicotine. C57BL/6J (B6J) mice are nicotine-preferring, while DBA/2J (D2J) mice are not. While the effects of menthol on oral nicotine consumption have been highlighted in B6J mice, it is unknown if they extend to the D2J strain as well. Consequently, adolescent (PND 21) and adult (PND 63), male and female D2J mice were subjected to the nicotine two-bottle choice (2BC) paradigm with orally and systemically administered menthol. Then, we evaluated its impact on nicotine pharmacological responses in conditioned reward and nociception after systemic administration and, lastly, investigated the potential involvement of the TAAR1 gene and α7 nAChRs in menthol’s effects. Menthol failed to enhance oral nicotine consumption in adult and adolescent female and male D2J mice. Moreover, this lack in effect was not due to nicotine concentration, oral aversion to menthol, or basal preference for nicotine. Menthol also failed to augment nicotine reward or enhance nicotine-induced antinociception in D2J mice, demonstrating that genetic background plays a significant role in sensitivity to menthol’s effects on nicotine. Furthermore, TAAR1 or α7 nAChRs did not seem to mediate menthol’s differential effects in D2J mice. These findings support the existence of genotype-specific mechanisms that may contribute to the variable effects of menthol in different populations.

Elevated homocysteine with pseudo-homozygosity for MTHFR677T as predisposing factors for transient ischemic attacks: a case report

A 21 year old male presented with a history of intermittent, transient neurological events. A brain MRI showed an area of restricted diffusion in keeping with an infarct, and an angiogram demonstrated an intracranial stenosis in the internal carotid artery, consistent with atherosclerosis. Laboratory investigations revealed a highly elevated plasma homocysteine, with low plasma folate and 5-methyltetrahydrofolate and methionine at the lower end of the normal ranges. The homocysteine normalized following treatment with folic acid. Molecular analysis found heterozygosity for the common MTHFR c.665C > T (aka 677C > T) variant and heterozygosity for a c.3G > C nucleotide substitution, which result in the lack of translation from this allele. It is proposed that the loss of p. Met1, coupled with folate deficiency, may be significant for the remethylation process, and may have contributed to the neurological events in this patient. If the two genetic variants are on alternate alleles, the patient would present with pseudo-homozygosity for MTHFR677T. It is probable that the combination of pronounced dietary folate deficiency, an MTHFR 'null allele' and the 677 T variant is sufficient to explain both the moderate hyperhomocysteinaemia and the clinical presentation in this patient. This case highlights the need to investigate other possible mutations in MTHFR, particularly in the absence of homozygous MTHFR 677C > T status in premature cardiovascular events.

Initiating antiretroviral treatment in a resource-constrained setting: does clinical staging effectively identify patients in need?

In industrialized countries, the initiation of antiretroviral therapy (ART) is based on virological, immunological and clinical markers. The objective of this study was to identify treatment gaps when ART initiation is based on clinical staging alone. The method employed was a retrospective study of 5784 patients enrolled in an HIV treatment programme in two urban and two rural sites in Ghana. Of the patients, 29.5% were in clinical Stages I and II and had a CD4+ T-lymphocyte count less than 200 cells/mm(3). Significantly more patients in clinical Stage I from urban sites (37.0%) had a CD4+ T-lymphocyte count less than 200 cells/mm(3) as compared with patients from rural sites (23.8%) (P value <0.05). In addition, more men (39.9%) in clinical Stage I had a CD4+ T-lymphocyte count less than 200 cells/mm(3) when compared with women (27.4%) (P value <0.05). In conclusion, clinical staging cannot identify a relatively large number of patients who need ART. A wider availability of CD4+ T-lymphocyte count testing will optimize the identification of patients eligible for ART.

Exercise training increases insulin-stimulated glucose disposal and GLUT4 (SLC2A4) protein content in patients with type 2 diabetes

AIMS/HYPOTHESIS

Exercise enhances insulin-stimulated glucose transport in skeletal muscle through changes in signal transduction and gene expression. The aim of this study was to assess the impact of acute and short-term exercise training on whole-body insulin-mediated glucose disposal and signal transduction along the canonical insulin signalling cascade.

METHODS

A euglycaemic-hyperinsulinaemic clamp, with vastus lateralis skeletal muscle biopsies, was performed at baseline and 16 h after an acute bout of exercise and short-term exercise training (7 days) in obese non-diabetic (n=7) and obese type 2 diabetic (n=8) subjects.

RESULTS

Insulin-mediated glucose disposal was unchanged following acute exercise in both groups. Short-term exercise training increased insulin-mediated glucose disposal in obese type 2 diabetic (p<0.05), but not in obese non-diabetic subjects. Insulin activation of (1) IRS1, (2) IRS2, (3) phosphotyrosine-associated phosphatidylinositol-3 kinase activity and (4) the substrate of phosphorylated Akt, AS160, a functional Rab GTPase activating protein important for GLUT4 (now known as solute carrier family 2 [facilitated glucose transporter], member 4 [SLC2A4]) translocation, was unchanged after acute or chronic exercise in either group. GLUT4 protein content was increased in obese type 2 diabetic subjects (p<0.05), but not in obese non-diabetic subjects following chronic exercise.

CONCLUSIONS/INTERPRETATION

Exercise training increased whole-body insulin-mediated glucose disposal in obese type 2 diabetic patients. These changes were independent of functional alterations in the insulin-signalling cascade and related to increased GLUT4 protein content.

A UML approach to process modelling of clinical practice guidelines for enactment

Although clinical practice guidelines (CPGs) have been suggested as a means of encapsulating best practice in evidence-based medical treatment, their usage in clinical environments has been disappointing. Criticisms of guideline representations have been that they are predominantly narrative and are difficult to incorporate into clinical information systems. This paper analyses the use of UML process modelling techniques for guideline representation and proposes the automated generation of executable guidelines using XMI. This hybrid UML-XMI approach provides flexible authoring of guideline decision and control structures whilst integrating appropriate data flow. It also uses an open XMI standard interface to allow the use of authoring tools and process control systems from multiple vendors. The paper first surveys CPG modelling formalisms followed by a brief introduction to process modelling in UMI. Furthermore, the modelling of CPGs in UML is presented leading to a case study of encoding a diabetes mellitus CPG using UML.