Starvation early

Starvation and incubation with labeled dextran For this method, cells are incubated under starvation [Earle s balanced salt solution (BBSS) medium] conditions for two hours. To label early endocytic compartments, cells are subsequently incubated with 0.5 mg/mL dextran tetramethylrhoda-mine for five minutes. To label late endosomes, cells are washed and further incubated for an additional 10 minutes (130). 

Appropriate management of AN also requires the early detection and treatment of any comorbid psychiatric disorders. The most common comorbid conditions associated with AN are major depressive disorder (MDD), obsessive-compulsive disorder (OCD), and substance use disorders. At the time of presentation, over 50% of AN patients also fulfill criteria for MDD however, accurate diagnosis of depression in these patients is complicated by the fact that prolonged starvation often produces a mood disturbance and neurovegetative symptoms identical to MDD. If MDD appears to be comorbid with AN at the time of presentation, there is debate as to whether it is more prudent to withhold treatment of the depression until weight restoration has been initiated. If the depression persists despite refeeding, then treatment of the depression is likely warranted. 

Self-inflicted starvation was not uncommon in early religious groups, so that anorexia nervosa may have occurred in the medieval periods but Richard Martin is usually credited with the first medical description in 1689 1 do not remember that 1 ever did in all my practice see one, that was conversant with living so much wasted with the greatest degree of consumption (Uke a skeleton only clad with skin) . 

On the basis of the resnlts with the obese, starvation can be divided arbitrarily into five phases the postabsorptive period, early starvation, intermediate starvation, prolonged starvation and, finally, the premortal period. Although these are characterised by different metabolic patterns, the transition from one period to another is gradnal. Some of the changes in the postabsorptive period and early starvation are described elsewhere in this book bnt they are bronght together in this chapter for completeness. 

Figure 16.8 Pattern of fuel mobitisatton and utUisatton during early starvation. This is starvation over a period of about 24 hours liver glycogen stores are nearly depleted and fatty acid mobilisation is taking place.

Risk assessment is both old and new. Old in the sense that humans and animals survive by evaluating the risk of harm verses the benefits of action. For early humans, the hunt for food or eating a new plant involved risk of harm, but doing nothing risked starvation. In our current society, this kind of informal risk assessment is now more directed towards the risks of eating undercooked hamburger or riding a bicycle without a helmet. More formally, risk assessment now refers to a mathematical calculation of risk based on toxicity and exposure. 

Many investigations were made by early workers using techniques such as starvation and pancreatectomy, but these for the most part gave equivocal results (for summary see Williams35), probably because the close interrelation of fat, protein and carbohydrate metabolism was not then fully appreciated and because the analytical methods used were often... 

Fig. 3. A northern blot of poly(A)+ RNA probed with a psi cDNA clone showed enhanced levels of psi messenger RNA as phosphate starvation became more severe. Poly(A)+ RNA was isolated from cultures at 3, 6 and 9 days after transfer to —Pi or +Pi medium (A. Danon et al., unpublished data in preparation). Equal amounts of RNA (1 pg per treatment) were separated on a denaturing formaldehyde/agarose gel and used for a northern blot. The filter was probed using a psi cDNA clone (identified by —/+ screening using standard methods) as the probe. Enhanced levels of mRNA for this clone are seen as early as 3 days after transfer to —Pi medium although cell growth equivalent to the unstressed control continued until day 8.

In addition to regulation involving quantitative changes in protein levels, we have identified at least one apparent psi protein phosphorylation event (Fig. 7). This high molecular weight phosphoprotein appears early in Pi starvation and is not excreted into the medium. The function of this molecule in psi metabolism is unknown. 

From the beginning of recorded history, weeds have limited man s food supply and have imposed a heavy labor burden. Nearly all of early man s time was no doubt spent in obtaining food. Natural food sources permitted man s survival, even though periods of starvation must have been common. From 10,000 B.C. to 6,000 B.C., man began to cultivate crops by primitive methods (Fig. 1) (JL). About 6,000 B.C., he fashioned hand-weeding tools. Around 1,000 B.C., animal-powered implements were introduced. Prior to this time, human energy was the sole source available for weed control. 

Starvation. The early reports that Hill inhibitors limited photosynthesis and that starch disappeared from treated plants, prompted some investigators to refer to these compounds as photosynthesis inhibitors. Photosynthesis is inhibited because ATP and NADFH are not available for carbon dioxide fixation. However, there is little evidence that the plants starve to death. If this were the only process affected, phytotoxic symptoms should resemble those that appear on plants kept in total darkness. Deficiency of photosynthate does limit new growth, but does not account for the morphological alterations that occur within a few hours after treatment. The mechanisms that lead to phytotoxicity appear to be considerably more complex than would result from limiting carbohydrate synthesis by suppression of carbon dioxide fixation (2). ... 

Which is the most dramatic difference between metabolic states observed in the early and prolonged starvation stages ... 

Prolonged starvation differs from early starvation in that... 

The correct answers are a and b (see Table 21.3). Glycerol and fatty acid production remain the same in early and prolonged starvation. 

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