The Puzzling Question

Induction of iNOS in human cell types and tissues has been difficult to characterize. Although multiple cell types in humans can be induced to express iNOS mRNA, the degree of activation is less robust than that seen in rodent cells. In vivo evidence of the relevance of iNOS in health and disease is provided by the work of Hibbs et al. (1992). IL-2 chemotherapy for malignant melanoma and renal cell carcinoma produces a septic-shock-like state that is associated with activation of the L-arginine-NO signaling pathway. Why cells derived from rodents and humans differ in their responsiveness is not clear. A working hypothesis is that the promoter for human iNOS is under tighter transcriptional control and/or less active compared to that in the mouse or the rat. 

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From a clinical point of view, drug taking is a complex behavior that involves consciousness and deliberate actions. The drug taker has to procure the drug or accept an offer. Consumption further involves a varied set of actions and procedures. This behavior clearly involves series of choices. The puzzling question is, therefore, why any individual continues to make what he or she—and certainly we—judge to be poor choices, choices of regret and poor net result. 

If this were not the case we would be faced with the puzzling question. Since the value of T, is higher when there are fewer CH2 units in the polymer, and therefore less hydrophobic hydration, why should a higher temperature be required to melt the lesser amount of more poorly structured hydrophobic hydration The thermally-induced inverse temperature transition does not result from a thermal destructuring of hydrophobic hydration, as we, with others, have indicated in the past (See for example the upper right illustration in Figure 2.8). ... 

The puzzling question is how to reconcile the variety of responses to the lipolytic and antilipolytic hormones, with a single common mechanism of action. 

Early work on the first members of the enolase superfamily to be discovered showed that the tertiary structures of two enzymes, MR and MLE, were highly similar despite a fairly low level of sequence similarity. The active sites of the two enzymes were found to share distinctly similar geometries as well (Figure I). But while these structural similarities implied a correlated functional similarity, examination of the chemical reactions of MR and MLE suggested, instead, profound dissimilarities. Not only were the overall reactions of MR and MLE distinct, their substrates were very different as well (Scheme I). This raised the puzzling question how could two such functionally dissimilar enzymes share such profoundly similar protein scaffolds ... 

All these techniques have provided a unanimous answer to the above questions. A combination of the results of any two or three of them would have sufficed to put together the puzzle. But each one of them has something new to offer, some new facet of the surface chemistry to reveal. So each of them will be discussed in this chapter in a sequence which in many cases coincides with the chronological order in which they were employed in order to solve the puzzle and understand the origin of electrochemical promotion. 

Only in recent years has progress been made in attacking the problem presented by these intermetallic compounds at the present time we may say that, although there are a number of puzzling questions that remain unanswered, the beginning of a theory of the stability and other properties of the substances has been formulated. 

Abstract. We present preliminary results of an extensive low and high-resolution ESO-VLT spectroscopic survey of Subgiant stars in the stellar system uj Centauri. Basing on infrared Ca II triplet lines we derived metallicities and radial velocities for more than 110 stars belonging to different stellar populations of the system. The most metal rich component, the SGB-a, appears to have metallicity [Fe/H] -0.5. Moreover, SGB-a stars have been found to stray from the dynamical behaviour of the bulk population. Such evidence adds new puzzling questions on the formation and the chemical enrichment history of this stellar system. 

Occasionally, some of the topics or puzzles in this book will seem simple or frivolous, including dropping pennies from the Empire State Building or wondering if Jesus could calculate 43 x 31. However, these are questions that fans have often posed to me, and I love some of these quirkies the best. I agree with the Austrian physicist Paul Ehrenfest who said Ask questions. Don t be afraid to appear stupid. The stupid questions are usually the best and hardest to answer. They force the speaker to think about the basic problem. ... 

The puzzling thing about GaN is that it shouldn t work as a microelectronic material it is just too riddled with crystal dislocations. If GaAs has more than 1000 dislocations per square centimetre it is unable to function as an LED, yet GaN can have a billion dislocations per square centimetre and still work. How does GaN accomplish this mission impossible As yet there is no dear answer to this question although it has something to do with the interface between the p- and n-forms of the semiconductor. The p-GaN is obtained by adding traces... 

Interestingly, the answer to this question remains unclear. So far the only mechanisms proposed by traditional studies in this area assume simple diffusion paths from capillaries and calculate smooth diffusion gradients within the cell ending in mitochondrial 02 sinks. However, this approach has been less than satisfactory for, to unravel the puzzle of how... 

Could some order be found in this body of diverse atoms Was there any connection between these elements Could some system of evolution or development be traced among them, such as Darwin, ten years before, had found among the multiform varieties of organic life Mendel eff wondered. The problem haunted his dreams. Constantly his mind reverted to this puzzling question. 

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