Selenium/cadmium ratios in human prostates

Selenium (Se) in a large-scale human supplementation trial has been shown to significantly reduce the incidence of prostate cancer in elderly men. Because Se is known to interact with cadmium (Cd), it has been suggested that its cancer protective action could be attributable in part to its interaction with Cd, a toxic and suspected carcinogenic element, which is found in many foods, in drinking water, and in the environment. Cadmium is considered a significant prostate cancer risk factor as it stimulates the growth of prostate epithelial cells and promotes their malignant transformation. Accordingly, prostate cancer risk is determined not only by Se status, but also the degree of Cd exposure. Determinations of Se and Cd in 129 prostates of deceased men aged 15–99 yr revealed Cd to accumulate in the prostate. Whereas the atomic Se/Cd ratios of the prostates of young men were invariably >1, indicating a stoichiometric excess of Se over Cd, they were found to decline with age, approaching the 1∶1 ratio in elderly nonsmokers, a fact suggestive of the formation of a 1∶1 Cd−Se complex. The associated physiological inactivation of Se could account for the increase of the prostate cancer risk with advancing age. The Se/Cd ratios dropped more steeply and consistently with age in smokers than in nonsmokers. In the prostates of some smokers, Se/Cd ratios even reached values <1, indicating a stoichiometric excess of Cd over Se. The excessive accumulation of Cd in the prostates of smokers along with sub-optimal Se intakes could explain why smokers develop more aggressive and lethal forms of prostate cancer than nonsmokers.     

On cloning human beings

The purpose of this paper is to show that arguments for and against cloning fail to make their case because of one or both of the following reasons: 1) they take for granted customary beliefs and assumptions that are far from being unquestionable; 2) they tend to ignore the context in which human cloning is developed. I will analyze some of the assumptions underlying the main arguments that have been offered for and against cloning. Once these assumptions are critically analyzed, arguments both rejecting and supporting human cloning seem to lose weight. I will first briefly present the main arguments that have been proposed against cloning and I will argue that they fail to establish their case. In the next section I will evaluate some of the positive arguments that have been offered supporting such technology. This analysis will show that the case for cloning also fails. Finally, I will maintain that because critics and especially supporters of this technology neglect the context in which human cloning is developed and might be implemented, their arguments are far from compelling.     

Bioavailability of seaweed iodine in human beings.

The major procedure used to correct iodine deficiency is the universal salt iodization by addition of iodide or iodate to salt with an iodine content varying from 7 to 100 mg/kg of salt depending on the country legislation. As an important fraction of consumers in the world prefers natural products over artificial ones, we investigated the industrial feasibility of naturally iodized salt using seaweed as source of iodine. We report the results of the iodine bioavailability in healthy subjects from two seaweeds: Laminaria hyperborea and Gracilaria verrucosa selected due to their high level in iodine as a mineral or an organic form and low levels of heavy metals. As a control we studied in a normal man the bioavailability of pure mineral iodine such as potassium iodide which was excellent i.e. 96.4% and of pure organic iodine such as monoiodotyrosine which was a little lower i.e. 80.0%. Iodine bioavailability from these two seaweeds was studied in nine normal subjects from Marseille (France) which is an iodine sufficient area based on a median urinary iodine level of 137 microg/day and innine normal subjects from Brussels (Belgium) who present a mild iodine deficiency with a value of 73 microg/day. The iodine bioavailability of Gracilaria verrucosa is better than for Laminaria hyperborea (101% versus 90% in Marseille, t=0.812, NS; 85% versus 61.5% in Brussels, t = 2.486, p = 0.024, S*). The urinary excretion of iodine is lower in Brussels than in Marseille for the same seaweed because part of the iodine is stored in the thyroid (101% versus 85% for Gracilaria verrucosa, t = 1.010, NS; 90% versus 61.5% for Laminaria hyperborea, t = 3.879, p= 0.001, S***).     

Comparison of tracheal mucous transport in rats, guinea pigs, rabbits, and dogs

Tracheal mucous transport was measured using similar techniques in several species. One- to 10-microliter quantities of 99mTc-macroaggregated albumin (99mTc-MAA) were instilled via oral intubation in the distal trachea of rats, rabbits, and dogs. Tracheostomies were used for the instillation in guinea pigs. All animals were anesthetized with halothane for the instillation and allowed to recover immediately in restrainers. Clearance of the 99mTc-MAA in rats and guinea pigs was measured by a slit-collimated NaI scanner. In rabbits and dogs a series of gamma-camera scintiphotos were taken. Clearance was faster and more efficient in dogs than in the other species. No significant differences existed among the rats, rabbits, and guinea pigs in the percentages of the originally deposited material remaining at the instillation site after 1 h (P greater than 0.2). Mean values and standard deviations were 83 +/- 23%, 81 +/- 22% and 70 +/- 20% for rats, guinea pigs, and rabbits, respectively. However, in the dogs a mean of 14 +/- 12% remained at the original site of deposition after only 25 min indicating much more rapid clearance. Mean leading-edge velocities were 9.8 +/- 2.1 (SD) for dogs, 3.2 +/- 1.1 for rabbits, 2.7 +/- 1.4 for guinea pigs, and 1.9 +/- 0.7 mm/min for rats. Clearance patterns qualitatively among the species. In dogs the material moved as a few discrete boluses, whereas in the other species the activity spread toward the larynx. The relatively slow mucous transport of rats, rabbits, and guinea pigs could have important implications in inhalation toxicological studies.     

Pharmacokinetics of phosphocreatine in the blood serum of man, dogs and rabbits

It is shown that a single intravenous injection of phosphocreatine to man or to experimental animals is followed by its rapid clearance from blood serum. This clearance is biphasic in nature with a half-life of 3-5 min at the first rapid stage and of 20-33 min at the next slower stage. To maintain the constant phosphocreatine concentration in blood, it is necessary to infuse it at a rate comparable to that of clearance. In particular, in blood serum of man, the phosphocreatine concentration can be kept at the level of 0.2 mM if it is injected at a rate of 60 mg/h per kg bw.