Fetal Pain: An Infantile Debate

The question of whether a fetus can experience pain is an immense challenge. The issue demands consideration of the physical and psychological basis of being and the relation between the two. At the center of this debate is the question of how it is that we are conscious, a question that has inspired the writing of some of our most brilliant contemporary philosophers and scientists, with one commentary suggesting surrender. In my earlier review I attempted to draw together the various strands of thinking that had attacked the question of fetal pain and relate them back to the bigger question of consciousness. In their vituperative response, Benatar and Benatar bite off my finger before looking to where I am pointing. I will examine each of their criticisms and attempt to redirect the readers' interest towards examining the subjectivity of pain and the mediating links between physiology and experience.     

An in vitro Analogue of Early Chick Limb Bud Outgrowth

Our culture system appears to represent an in vitro analogue of early chick limb morphogenesis. Organized mesodermal cell accumulations resembling limb buds were derived from a monolayer of limb mesoderm cells when covered by limb ectoderm which included the apical ectodermal ridge (AER). The ridge retained its normal configuration when grown over a limb mesoderm monolayer and the mesoderm cells accumulated under the ridge to form a multilayered structure (10–25 cells in thickness) with the characteristic shape of a limb bud. Ectoderm which did not include the ridge failed to promote the formation of limb-like mesodermal accumulations thus the action of the ridge appears to be specific. The AER-elicited expression of mesodermal cell behaviour leading to early limb outgrowth is discussed in terms of possible morphogenetic mechanisms involved i.e. differential mitosis, cell migration, changes in cell shape and especially the adhesive properties of the cells.     

An 82-Kilodalton Membrane Protein that Inhibits the Activity of Neurite Outgrowth Factor

Neurite outgrowth factor (NOF), an extracellular matrix glycoprotein of 700 kilodaltons (kDa), promoted neurite outgrowth from cultured ciliary ganglion (CG) neurons of chicken embryo. A fraction solubilized with Nonidet P-40 of chicken gizzard muscle membranes inhibited the neurite-promoting activity of NOF in a dose-dependent manner, but not that of laminin. Binding of CG neurons to the substratum and their survival were not affected by the extract. The inhibitory activity of the extract was abolished by treatment with trypsin or heat. The molecular size was determined to be about 82 kDa by ligand blotting. The active component was partially purified by column chromatography. It is suggested that this molecule interacts with the domain of NOF responsible for its neurite-promoting activity and may modulate NOF activity during development in vivo.     

Being an Only or Last-Born Child Increases Later Risk of Obesity

Background

Studies have suggested that number of siblings and birth order is associated with obesity. However, studies combining these exposures are needed. This study aimed at investigating obesity in children and young adults in regard to different combinations of family size and birth order.

Methods

Two cohorts selected from the general population were investigated: The Copenhagen School Health Records Register (CSHRR) and a Draft Board (DB) sample with measured heights and weights in childhood (age 13 years) and young adulthood (age 19 years), respectively. Information on birth order, number of siblings, and relevant covariates were available on 29 327 children, as well as on 323 obese young men and 575 randomly selected controls of young men representing approximately 58 000. The relation between number of siblings and birth order, respectively, and having a Body Mass Index (BMI) z-score above or equal to the 95^th percentile in childhood or having a BMI of at least 31.00 kg/m² in young adulthood was analysed using logistic regression analyses adjusted for relevant confounders.

Results

Only children had significantly higher odds of obesity both in childhood and in young adulthood compared with children with siblings, odds ratio (OR) = 1.44 (95% Confidence Interval (CI): 1.26–1.66) and OR = 1.76 (95% CI: 1.18–2.61), respectively. No association between first-born status and obesity was found. The OR of last-born children being obese was also significantly increased in childhood, e.g. OR = 1.93 (95% CI: 1.09−3.43) of obesity if last-born in a family of four children. This was not found in young adulthood. Additionally, higher spacing to previous sibling (average 1872 vs. 1303 days; p = 0.026 in four children families) was observed in obese last-born compared to non-obese last-born children.

Conclusion

Being an only or last-born child is associated with obesity. These associations may provide leads to targeted prevention of obesity in children.     

Pain Perception in the Elderly Patient: An Overview of Issues

The control of pain is an issue of major importance for older patients. As the proportion of elderly persons in society grows, these problems take on particular humanitarian and economic significance. Review of the literature indicates that the sensory mechanisms subserving pain in older persons are not unique, but painful pathologic states are more likely to occur in old age. Stereotypes of the older person have led to insufficient management and overmedication of this patient population. Moreover, the complex nature of chronic pain in the aged patient has not been appreciated by health care professionals. The literature points to an urgent need for more data that will shed light on the nature of pain problems in old age.     

Trials, Travails and Triumphs: An Account of RNA Catalysis in RNase P

Last December marked the 20th anniversary of the Nobel Prize in Chemistry to Sidney Altman and Thomas Cech for their discovery of RNA catalysts in bacterial ribonuclease P (an enzyme catalyzing 5′ maturation of tRNAs) and a self-splicing rRNA of Tetrahymena, respectively. Coinciding with the publication of a treatise on RNase P,¹ this review provides a historical narrative, a brief report on our current knowledge, and a discussion of some research prospects on RNase P.

“…the great thing about science is that you can actually solve a problem. You can take something which is confused, a mess, and not only find a solution, but prove it's the right one.”²

-Sydney Brenner

“In research the front line is almost always in a fog.”³

-Francis Crick

     

Saccadic Compression of Rectangle and Kanizsa Figures: Now You See It,Now You Don't

Background

Observers misperceive the location of points within a scene as compressed towards the goal of a saccade. However, recent studies suggest that saccadic compression does not occur for discrete elements such as dots when they are perceived as unified objects like a rectangle.

Methodology/Principal Findings

We investigated the magnitude of horizontal vs. vertical compression for Kanizsa figure (a collection of discrete elements unified into single perceptual objects by illusory contours) and control rectangle figures. Participants were presented with Kanizsa and control figures and had to decide whether the horizontal or vertical length of stimulus was longer using the two-alternative force choice method. Our findings show that large but not small Kanizsa figures are perceived as compressed, that such compression is large in the horizontal dimension and small or nil in the vertical dimension. In contrast to recent findings, we found no saccadic compression for control rectangles.

Conclusions

Our data suggest that compression of Kanizsa figure has been overestimated in previous research due to methodological artifacts, and highlight the importance of studying perceptual phenomena by multiple methods.     

An Attempt to Account for the Diversity of Crustacean Muscles

Crustacean muscles are known to contain muscle fibers of variableproperties and to be innervated by phasic and/or tonic motoneuronswhich may possess synapses of diverse physiological properties.Frequently, phasic motor axons innervate short-sarcomere phasicmuscle fibers and tonic motor axons innervate long-sarcomeretonic muscle fibers, but some muscles receiving a single (tonic)motor axon contain both phasic and tonic muscle fibers. Althoughit is not known whether neural trophic influences are involvedin muscle differentiation, some neural trophic effects havebeen found in crustaceans, and it is reasonable to assume thatsuch influences may be involved in establishing the definitiveproperties of the muscle. Several other postulates must be made:(1) Phasic and tonic motor axons differ in their trophic effectiveness:(2) muscle fibers innervated relatively early in developmentby a tonic motor axon acquire the properties of tonic musclefibers, while those innervated later become intermediate orphasic muscle fibers; (3) the developmental stage of a growingor regenerating axon terminal plays a role in determinationof synaptic properties. Studies on regenerating limb buds supportthe hypothesis, which can account for the genesis of all observedtypes of crustacean neuromuscular system. Further experimentalwork is necessary to test the hypothesis.