Agronomic and chemical performance of field-grown tobacco engineered for triterpene and methylated triterpene metabolism.

Squalene is a linear intermediate to nearly all classes of triterpenes and sterols and is itself highly valued for its use in wide range of industrial applications. Another unique linear triterpene is botryococcene and its methylated derivatives generated by the alga Botryococcus braunii race B, which are progenitors to fossil fuel deposits. Production of these linear triterpenes was previously engineered into transgenic tobacco by introducing the key steps of triterpene metabolism into the particular subcellular compartments. In this study, the agronomic characteristics (height, biomass accumulation, leaf area), the photosynthetic capacity (photosynthesis rate, conductance, internal CO2 levels) and triterpene content of select lines grown under field conditions were evaluated for three consecutive growing seasons. We observed that transgenic lines targeting enzymes to the chloroplasts accumulated 50-150 times more squalene than the lines targeting the enzymes to the cytoplasm, without compromising growth or photosynthesis. We also found that the transgenic lines directing botryococcene metabolism to the chloroplast accumulated 10- to 33-fold greater levels than the lines where the same enzymes were targeted to in the cytoplasm. However, growth of these high botryococcene accumulators was highly compromised, yet their photosynthesis rates remained unaffected. In addition, in the transgenic lines targeting a triterpene methyltransferase (TMT) to the chloroplasts of high squalene accumulators, 55%-65% of total squalene was methylated, whereas in the lines expressing a TMT in the cytoplasm, only 6%-13% of squalene was methylated. The growth of these methylated triterpene-accumulating lines was more compromised than that of nonmethylated squalene lines.

Susceptibility to nicotine dependence: the Development and Assessment of Nicotine Dependence in Youth 2 study.

OBJECTIVES: The purpose of this work was to identify characteristics that predict progression from the first inhalation of a cigarette to dependence. We studied a cohort of 1246 public school 6th-graders in 6 Massachusetts communities (mean age at baseline: 12.2 years). METHODS: We conducted a 4-year prospective study using 11 interviews. We assessed 45 risk factors and measured diminished autonomy over tobacco with the Hooked on Nicotine Checklist and evaluated tobacco dependence according to the International Classification of Diseases, 10th Revision. Cox proportional-hazards models were used. RESULTS: Among 217 youths who had inhaled from a cigarette, the loss of autonomy over tobacco was predicted by feeling relaxed the first time inhaling from a cigarette and depressed mood. Tobacco dependence was predicted by feeling relaxed, familiarity with Joe Camel, novelty seeking, and depressed mood. CONCLUSIONS: Once exposure to nicotine had occurred, remarkably few risk factors for smoking consistently contributed to individual differences in susceptibility to the development of dependence or loss of autonomy. An experience of relaxation in response to the first dose of nicotine was the strongest predictor of both dependence and lost autonomy. This association was not explained by trait anxiety or any of the other measured psychosocial factors. These results are discussed in relation to the theory that the process of dependence is initiated by the first dose of nicotine.

Symptoms of tobacco dependence after brief intermittent use: the Development and Assessment of Nicotine Dependence in Youth-2 study.

OBJECTIVE: To extend the findings of the first Development and Assessment of Nicotine Dependence in Youth study by using diagnostic criteria for tobacco dependence and a biochemical measure of nicotine intake. The first study found that symptoms of dependence commonly appeared soon after the onset of intermittent smoking. DESIGN: A 4-year prospective study. SETTING: Public schools in 6 Massachusetts communities. PARTICIPANTS: A cohort of 1246 sixth-grade students. INTERVENTIONS: Eleven interviews. MAIN OUTCOME MEASURES: Loss of autonomy over tobacco as measured by the Hooked on Nicotine Checklist, and tobacco dependence as defined in International Classification of Diseases, 10th Revision (ICD-10). RESULTS: Among the 217 inhalers, 127 lost autonomy over their tobacco use, 10% having done so within 2 days and 25% having done so within 30 days of first inhaling from a cigarette; half had lost autonomy by the time they were smoking 7 cigarettes per month. Among the 83 inhalers who developed ICD-10-defined dependence, half had done so by the time they were smoking 46 cigarettes per month. At the interview following the onset of ICD-10-defined dependence, the median salivary cotinine concentration of current smokers was 5.35 ng/mL, a level that falls well below the cutoff used to distinguish active from passive smokers. CONCLUSIONS: The most susceptible youths lose autonomy over tobacco within a day or 2 of first inhaling from a cigarette. The appearance of tobacco withdrawal symptoms and failed attempts at cessation can precede daily smoking; ICD-10-defined dependence can precede daily smoking and typically appears before consumption reaches 2 cigarettes per day.

Effects of an augmented postoperative fluid protocol on wound healing in cardiac surgery patients.

BACKGROUND: Cardiac surgery patients are vulnerable to hypoperfusion postoperatively and often have subcutaneous tissue oxygen tension less than 50 mm Hg. Hypovolemia most likely contributes to this hypoperfusion and may lead to impaired wound healing. OBJECTIVES: To determine if a modified postoperative fluid replacement protocol would result in improved tissue oxygen tension, blood flow, and healing in cardiothoracic surgery patients. METHODS: A total of 166 cardiac surgery patients, 18 to 90 years old, participated in a randomized, 2-group, repeated-measures study. The experimental group received fluid augmentation during the first 36 hours after surgery; the control group received standard postoperative replacement fluids. Subcutaneous tissue oxygen tension and temperature were measured 8, 18, and 36 hours after surgery. Tissue cellularity and accumulation of hydroxyproline were evaluated in tissue obtained from subcutaneous expanded polytetrafluoroethylene tubes. Wound complications were evaluated by using the ASEPSIS Wound Scoring System. RESULTS: Tissue oxygen levels, tissue cellularity, and accumulation of hydroxyproline were similar in the 2 groups. A negative correlation (P = .01) existed between higher tissue oxygen values and lower (better) ASEPSIS leg wound scores. More than 80% of the patients had tissue oxygen levels of 50 mm Hg or less at each time of measure. Many values were 30 to 40 mm Hg less than the ideal for control of bacteria and healing. CONCLUSIONS: The frequency of low oxygen levels is consistent with data from earlier studies. Determination of other interventions to improve subcutaneous tissue perfusion in cardiac surgery patients is needed.