Darwin's language may seem teleological,but his thinking is another matter

Darwin's biology was teleological only if the term teleology is defined in a manner that fails to recognize his contribution to the metaphysics and epistemology of modern science. His use of teleological metaphors in a strictly teleonomic context is irrelevant to the meaning of his discourse. The myth of Darwin's alleged teleology is partly due to misinterpretations of discussions about whether morphology should be a purely formal science. Merely rejecting such notions as special creation and vitalism does not prevent the pernicious effects of teleological reasoning, even at the present time.     

Unloaded rat Achilles tendons continue to grow, but lose viscoelasticity.

Tendons can function as springs and thereby preserve energy during cyclic loading. They might also have damping properties, which, hypothetically, could reduce risk of microinjuries due to fatigue at sites of local stress concentration within the tendon. At mechanical testing, damping will appear as hysteresis. How is damping influenced by training or disuse? Does training decrease hysteresis, thereby making the tendon a better spring, or increase hysteresis and thus improve damping? Seventy-eight female 10-wk-old Sprague-Dawley rats were randomized to three groups. Two groups had botulinum toxin injected into the calf muscles to unload the left Achilles tendon through muscle paralysis. One of these groups was given doxycycline, as a systemic matrix metalloproteinase inhibitor. The third group served as loaded controls. The Achilles tendons were harvested after 1 or 6 wk for biomechanical testing. An increase with time was seen in tendon dry weight, wet weight, water content, transverse area, length, stiffness, force at failure, and energy uptake in all three groups (P < 0.001 for each parameter). Disuse had no effect on these parameters. Creep was decreased with time in all groups. The only significant effect of disuse was on hysteresis (P = 0.004) and creep (P = 0.007), which both decreased with disuse compared with control, and on modulus, which was increased (P = 0.008). Normalized glycosaminoglycan content was unaffected by time and disuse. No effect of doxycycline was observed. The results suggest that in growing animals, the tendons continue to grow regardless of mechanical loading history, whereas maintenance of damping properties requires mechanical stimulation.     

Controlling a system with redundant degrees of freedom. I. Torque distribution in still standing stick insects

The question is investigated as to how a stick insect solves the task of distributing its body weight onto its six legs, i.e., how are the torques coordinated that are produced by the 18 joints (3 per leg). Three-dimensional force measurements of ground reaction forces have been used to calculate the torques developed by each of the 18 joints. Torques were found to change considerably although the body and the legs of the animal did not move. This result implies a tight cooperation between the 18 joint controllers. Indeed, in each individual experiment, strong correlations could be observed between specific pairs of joints. However, in spite of thorough analysis, no general correlation rules between torques could be detected. The only common attribute found for all experiments was that high absolute torques observed at the beginning of the experiment tend to converge to some minimum over time. Thus, the insects tend to decrease the torques while standing still, but do not use fixed rules. Rather they appear to exploit their extra degrees of freedom and produce time courses that can strongly vary between experiments. Possible mechanisms underlying this behaviour are discussed in a companion paper [Lévy and Cruse (2008) Controlling a system with redundant degrees of freedom: ii. solution of the force distribution problem without a body model, submitted].     

Chlamydia trachomatis has penicillin-binding proteins but not detectable muramic acid.

Chlamydia trachomatis LGV-434 was grown in HeLa 229 cells. Benzylpenicillin completely inhibited the formation of infectious elementary bodies (EBs) at a concentration of 19 pmol/ml or higher and produced abnormally large reticulate bodies (RBs) in the inclusions at 30 pmol/ml or higher. The possible targets for penicillin in C. trachomatis were three penicillin-binding proteins (PBPs) which were identified in the Sarkosyl-soluble fractions of both RBs and EBs. The apparent subunit molecular weights were 88,000 (PBP 1), 61,000 (BPB 2), and 36,000 (PBP 3). The 50% binding concentrations of [3H]penicillin for PBPs 1 to 3 in EBs and RBs were between 7 and 70 pmol/ml. Such high susceptibility to penicillin was shown by an organism that did not have detectable muramic acid (less than 0.02% by weight) in preparations of either whole cells or sodium dodecyl sulfate-insoluble residues.     

Thallium poisoning. Diagnosis may be elusive but alopecia is the clue.

Thallium is a heavy metal whose salts are used in some rodent poisons and in the manufacture of optical lenses, semiconductors, scintillation counters, low temperature thermometers, and switching devices, green coloured fireworks, and imitation jewelery, and as chemical catalysts. In clinical practice thallium isotopes are used in cardiac scanning, but the use of thallium salts to treat scalp ringworm was abandoned earlier this century because of their toxicity. The sale of thallium in Britain is strictly licensed because of its toxicity and potential for use in murder, which is helped by the fact that thallous salts are colourless, tasteless, and odorless. The more water soluble salts (such as thallium sulphate, acetate, or carbonate) have higher toxicity, and although the toxic dose is variable most deaths occur after the ingestion of 10-15 mg/kg of soluble salt. Most cases of thallium toxicity occur after oral ingestion but severe toxicity has been reported after inhalation of contaminated dust from pyrite burners, in zinc and lead smelting, and in the manufacture of cadmium, after dermal absorption through protective rubber gloves, and after snorting what was thought to be cocaine. The elimination half time of thallium is between 1.7 and 30 days depending on the time since, and chronicity of, ingestion. The elimination time phases are apparent and because of the long terminal elimination half time thallium may act as a cumulative poison. We present two cases of thallium poisoning with intent to kill.