Enantiomeric composition of N'-nitrosonornicotine and N'-nitrosoanatabine in tobacco

The tobacco-specific nitrosamines N'-nitrosonornicotine (NNN) and N'-nitrosoanatabine (NAT) are found in substantial quantities in unburned tobacco. Although this has been documented in many previous studies, no data are available on the enantiomeric composition of these nitrosamines, which both have a chiral center at their 2'-positions. We used chiral stationary phase gas chromatography with nitrosamine-selective detection to determine the enantiomeric composition of NNN and NAT in moist snuff, chewing tobacco, and cigarette tobacco. (S)-NNN comprised 75.0 +/- 8.83% (SD) (n = 12) of total NNN while (S)-NAT comprised 82.6 +/- 1.44% (n = 12) of total NAT. Levels of the (S)-enantiomers of NNN and NAT were generally similar to those of the corresponding secondary amines, nornicotine and anatabine, suggesting a precursor to product relationship. Nitrosation of (S)-nicotine at pH 7.0 produced >99% (S)-NNN. These results suggest that nornicotine is a significant precursor of NNN in tobacco. The results of this study provide new insights into the structures and precursors of tobacco-specific nitrosamines in tobacco products.     

Characterization of cord blood natural killer and lymphokine activated killer lymphocytes following ex vivo cellular engineering.

Cord blood (CB) natural killer (NK) and lymphokine-activated killer (LAK) cytotoxic cells are poorly characterized but might be used to treat minimal residual and/or recurrent malignant disease. Currently, there is no mechanism to use CB for adoptive cancer cellular immunotherapy after CB transplantation (CBT). Recognizing this as a deficiency, we hypothesized that CB aliquots could be engineered ex vivo for potential donor lymphocyte infusion after CBT. Cryopreserved CB aliquots were thawed, depleted of monocytes, and cultured in serum-free medium alone or serum-free medium with anti-CD3 and interleukins 2, 7, and 12 combined with antibody/cytokines for 48 hours. Immunophenotyping, cytotoxicity, and proliferation were evaluated. A significant expansion of CD3+ was seen, in addition to increases in lymphocyte subsets of CD8+, CD8+/CD25+, and CD3+/45RO+ versus medium alone. A significant enhancement of CD3 proliferation (P<.001), NK cytotoxicity, NK subset expansion, LAK cytotoxicity, and T-helper 1 subset expansion was also demonstrated. Significant enrichment was seen in NK CD16+/CD56+bright, CD16+/CD56+dim, CD56+bright and CD56+dim/KIR3DL1+, CD56+bright and CD56+dim/KIR2DL1+, CD56+bright and CD56+dim/KIR2DL2+ and CD94+/NKG2a+ subsets. These increases in CB NK subsets were in part secondary to augmentation of cell survival. Further, survival of NOD-SCID mice xenografted with human K562 cells and treated with CB cells expanded with antibody/cytokines was significantly higher than that in animals that received no treatment (phosphate buffered saline) and those that were treated with CB ex vivo expanded in medium alone (P<.005, respectively). These data suggest that cryopreserved CB cells could be ex vivo engineered for potential use as adoptive cancer cellular immunotherapy for donor lymphocyte infusion after CBT.     

Islet β-cell endoplasmic reticulum stress precedes the onset of type 1 diabetes in the nonobese diabetic mouse model

Type 1 diabetes is preceded by islet β-cell dysfunction, but the mechanisms leading to β-cell dysfunction have not been rigorously studied. Because immune cell infiltration occurs prior to overt diabetes, we hypothesized that activation of inflammatory cascades and appearance of endoplasmic reticulum (ER) stress in β-cells contributes to insulin secretory defects. Prediabetic nonobese diabetic (NOD) mice and control diabetes-resistant NOD-SCID and CD1 strains were studied for metabolic control and islet function and gene regulation. Prediabetic NOD mice were relatively glucose intolerant and had defective insulin secretion with elevated proinsulin:insulin ratios compared with control strains. Isolated islets from NOD mice displayed age-dependent increases in parameters of ER stress, morphologic alterations in ER structure by electron microscopy, and activation of nuclear factor-κB (NF-κB) target genes. Upon exposure to a mixture of proinflammatory cytokines that mimics the microenvironment of type 1 diabetes, MIN6 β-cells displayed evidence for polyribosomal runoff, a finding consistent with the translational initiation blockade characteristic of ER stress. We conclude that β-cells of prediabetic NOD mice display dysfunction and overt ER stress that may be driven by NF-κB signaling, and strategies that attenuate pathways leading to ER stress may preserve β-cell function in type 1 diabetes.     

Management of patients in the intensive care unit: comparison via work sampling analysis of an acute care nurse practitioner and physicians in training.

BACKGROUND: Little is known about aspects of practice that differ between acute care nurse practitioners and physicians that might affect patients' outcomes. OBJECTIVE: To determine if time spent in work activities differs between an acute care nurse practitioner and physicians in training (pulmonary/critical care fellows) managing patients' care in a step-down medical intensive care unit. METHODS: Work sampling techniques were used to collect data when the nurse practitioner had 6 months' or less experience in the role (T1), after the nurse practitioner had 12 months' experience in the role (T2), and when physicians in training provided care on a rotational schedule (nurse practitioner not present, T3). These data were used to estimate the time spent in direct management of patients, coordination of care, and nonunit activities. RESULTS: Results for T1 and T2 were similar. When T2 and T3 were compared, the nurse practitioner and the physicians in training spent approximately half their time in activities directly related to management of patients (40% vs 44%, not significantly different). The nurse practitioner spent more time in activities related to coordination of care (45% vs 18%; P < .001) and less time in nonunit activities (15% vs 37%; P < .001). CONCLUSION: The nurse practitioner and the physicians in training spent a similar proportion of time performing required tasks. Because of training requirements, physicians spent more time than the nurse practitioner in nonunit activities. Conversely, the nurse practitioner spent more time interacting with patients and patients' families and collaborating with health team members.     

Palmitate Induces mRNA Translation and Increases ER Protein Load in Islet β-Cells via Activation of the Mammalian Target of Rapamycin Pathway

Saturated free fatty acids (FFAs) have complex effects on the islet β-cell, acutely promoting adaptive hyperplasia but chronically impairing insulin release. The acute effects of FFAs remain incompletely defined. To elucidate these early molecular events, we incubated mouse β-cells and islets with palmitate and then studied mRNA translation by polyribosomal profiling and analyzed signaling pathways by immunoblot analysis. We found that palmitate acutely increases polyribosome occupancy of total RNA, consistent with an increase in mRNA translation. This effect on translation was attributable to activation of mammalian target of rapamycin (mTOR) pathways via L-type Ca²⁺ channels but was independent of insulin signaling. Longer incubations led to depletion of polyribosome-associated RNA, consistent with activation of the unfolded protein response (UPR). Pharmacologic inhibition of mTOR suppressed both the acute effects of palmitate on mRNA translation and the chronic effects on the UPR. Islets from mice fed a high-fat diet for 7 days showed increases in polyribosome-associated RNA and phosphorylation of S6K, both consistent with activation of mTOR. Our results suggest that palmitate acutely activates mRNA translation and that this increase in protein load contributes to the later UPR.