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A major limitation of intact protein fragmentation is the lack of sequence coverage within proteins’ interiors. We show that collisionally activated dissociation (CAD) produces extensive internal fragmentation within proteins’ interiors that fill the existing gaps in sequence coverage, including disulfide loop regions that cannot be characterized using terminal fragments. A barrier to the adoption of internal fragments is the lack of methods for their generation and assignment. To provide these, we explore the effects of protein size, mass accuracy, internal fragment size, CAD activation energy, and data preprocessing upon the production and identification of internal fragments. We also identify and mitigate the major source of ambiguity in internal fragment identification, which we term “frameshift ambiguity.” Such ambiguity results from sequences containing any “middle” portion surrounded by the same composition on both termini, which upon fragmentation can produce two internal fragments of identical mass, yet out of frame by one or more amino acids (e.g., TRAIT producing TRAI or RAIT). We show that such instances permit the a priori assignment of the middle sequence portion. This insight and our optimized methods permit the unambiguous assignment of greater than 97% of internal fragments using only the accurate mass. We show that any remaining ambiguity in internal fragment assignment can be removed by consideration of fragmentation propensities or by (pseudo)-MS3. Applying these methods resulted in a 10-fold and 43-fold expanded number of identified ions, and a concomitant 7- and 16-fold increase in fragmentation sites, respectively, for native and reduced forms of a disease-associated SOD1 variant.

This study investigated the effect of long-term high-fat sucrose (HFS) or low-fat complex-carbohydrate (LFCC) diet consumption on leptin, insulin, fat cell size, energy intake, and markers of activity to ascertain the role that leptin plays in long-term energy balance in a model of diet-induced obesity. Female Fischer 344 rats were fed either a HFS or LFCC diet ad libitum for a period of 20 mo. Measurements of leptin concentration, insulin concentration, and adipocyte size were performed at 2 wk, 2 mo, 6 mo, and 20 mo. Body weight and energy intake were measured weekly for calculation of feed efficiency. Body temperature and activity levels were assessed over a 5-day period after 12 mo of the dietary intervention. Plasma leptin and insulin concentrations were significantly elevated within 2 wk of HFS diet consumption and remained elevated throughout the course of the study. After 2 mo, the adipocytes of the HFS group were significantly larger and continued to increase in size throughout the course of the study. A significant correlation was noted between leptin and adipocyte cell size (r = 0.96,P< 0.01). However, despite elevated leptin, energy intake was similar, and the HFS group weighed significantly more than the LFCC group, as a result of a higher feed efficiency. There were no significant differences in body temperature or activity levels between the groups. These results demonstrate that a HFS diet causes hyperleptinemia and hyperinsulinemia before adipocyte size is increased and suggests that leptin resistance may be present or, alternatively, that leptin does not to play a major role in the long-term regulation of energy intake or activity levels in this model.

This study was designed to examine the relationship between diet-induced insulin resistance/hyperinsulinemia, fat cell hypertrophy, and hormone-sensitive lipase (HSL) to elucidate whether an attenuated HSL activity leads to obesity. Female Fischer 344 rats were fed either a low-fat, complex-carbohydrate diet or a high-fat, refined-sugar (HFS) diet for 2 wk, 2 mo, or 6 mo. Adipose tissue morphology and HSL activity as well as plasma free fatty acid and glycerol levels were determined at these times. No differences between groups were seen after 2 wk except the previously reported hyperinsulinemia in the HFS animals. At both 2 and 6 mo, the HFS animals demonstrated adipocyte hypertrophy. Basal and stimulated HSL activities and plasma glycerol were significantly elevated in the HFS group. There was a positive correlation between adipocyte size and HSL activity for both basal and stimulated states. These results demonstrate that an attenuated HSL activity is not observed with the onset of insulin resistance/hyperinsulinemia and therefore does not play a role in the development of obesity.

This study was designed to examine the effects of a high-fat refined-sugar (HFS) or a low-fat complex-carbohydrate (LFCC) diet on insulin-stimulated skeletal muscle glucose transport, plasma insulin, blood pressure, plasma triglycerides, plasma glycerol, body weight, and body fat in female Fischer rats. Insulin-stimulated glucose transport was significantly reduced in the HFS group at 2 wk, 2 mo, and 2 yr, whereas serum insulin was significantly elevated at all time points. Blood pressure was not significantly elevated in the HFS group until 12 mo, and all HFS animals were hypertensive by 18 mo. Glycerol, triglycerides, and abdominal fat cell size were not significantly different at 2 wk but were significantly elevated in the HFS rats at 2 and 6 mo. Body weight was similar in both groups until 20 wk on the diet, when the HFS rats started to gain more weight. These results demonstrate that insulin resistance and hyperinsulinemia occur before the other manifestations of the metabolic syndrome and that diet, not obesity, is the underlying cause.

The poem "Spork," by Joshua Berger is presented. First Line: May I sit with you? Asked the spork, Last Line: Only that the's different.

The article discusses the project assigned to Plazm Media by MTV. The project involves creating a new typeface for the channel to be used as the primary on-air presence. The author declares that Plazm Media approached the project with their publishing and print experience and a recognition of MTV's impact on music, fashion and film. It began in mid-July and was completed by September 1, 1997.

The article reports on the assertion that people of Mississippi are in the interest to elect presidential candidate Barack Obama in the U.S. According to chairman of the state Democratic party Jamie Franks, Obama plans to help most of Mississippians. State secretary for the Democrats Mona Pittman says the proposal of Obama to cut taxes for families that make less than a quarter-million dollars a year and to raise taxes for those that make more would give a boost to the Mississippi economy.