Euthanasia and the active-passive distinction

The author examines various claimed differences between active and passive euthanasia and, if there are differences, whether they are morally significant. He refutes arguments based on acting vs. not acting, intention, double effect, cause of death, and natural law theory. Reichenbach proposes that the most helpful distinction is the one between intentional killing (active euthanasia) and appropriate treatment for the dying or terminally ill (passive euthanasia). Significant moral difference, however, rests on the contention that intentional killing is always wrong and that, all else being equal, dying by natural means is intrinsically good, whereas dying by unnatural means is not.     

The effect of sucrose on the levels of abscisic acid, indoleacetic acid and zeatin/zeatin riboside in wheat ears growing in liquid culture

The influence of a varied sucrose supply on grain size and hormonal contents of detached wheat ears ( Triticwn aestivum L. cv. Schirokko) was investigated throughout grain development. In ears led limited amounts, or no sucrose, grain weights in both proximal and distal grain positions of the ear were reduced. Radioimmunoassay for abscisic acid, indoleacetic acid and zeatin/zeatin riboside showed that the changes in the levels of these hormones in grains and bracts were comparable to intact ears when detached ears were well supplied with sucrose. Under conditions of limited sucrose supply, higher abscisic acid levels in the distal and proximal grains of detached ears were found compared to ears supplied with adequate sucrose. Limiting sucrose supply to the ear did not alter the levels of indoleacetic acid or zeatin/zeatin riboside in either the grains or bracts of detached ears.     

Iron kinetics effects of 88 millirads. Partial-versus-total body X-irradiation

Rats were irradiated with one tibia shielded (95% marrow exposure), total body exposed (TBI, 100%), and only one tibia exposed (5%), or they were sham irradiated (SI, 0%). Plasma Fe-59 clearance time (T1/2) and Fe-59 content ratio in the right and left tibia (RT/LT) were assayed to determine the erythroid activity of the overall marrow of the animals and the relative marrow activity in the exposed and shielded tibias, respectively. When a major fraction of the overall marrow was shielded or irradiated, the overall erythroid activity levels were identical to those of the SI and TBI animals, respectively. Interestingly, enhanced normoblastosis was observed in the marrow of the exposed tibia of individual animals exhibiting normal erythroid activity in 95% of the marrow. Conversely, localized marrow with normal erythroid activity was found in a shielded tibia of individual rats, demonstrating an enhanced erythroid activity in a major fraction of the total body. It was concluded that 88 mrad can alter marrow functions in a small isolated skeletal region as effectively as in the whole body, and tandem assays of the Fe-59 T1/2 and Fe-59 RT/LT can facilitate ultra-low-dose X-ray studies involved with partial body exposures.     

Generalizing from experiments: is predation strong or weak in the New England rocky intertidal?

Summary Petraitis (1990) recently critized previous generalizations regarding the effects of predation in the New England rocky intertidal region (e.g., Menge 1976; Lubchenco and Menge 1978). Contrary to Lubchenco's and my conclusions, Petraitis concluded that (1) barnacles and not mussels are the favored prey of dogwhelks and (2) barnacles and not dogwhelks control mussel abundances in the mid and low rocky intertidal region. I provide evidence that these criticisms are unwarranted. First, Lubchenco and I never claimed that diet composition reflected prey preference. Moreover, predators can influence prey abundance without preferring the prey. Hence, claims regarding preferences have no bearing on our conclusions. Second, Petraitis' experiments do not invalidate Lubchenco's and my experimental results. Reanalyses of our experimental data support the earlier conclusion that at wave-sheltered sites, whelks reduce the abundance of mussels independently of barnacle abundances. Further, at all but one of Lubchenco's and my study sites, predator densities were higher than at Petraitis' site. Thus, the absence of a predator effect in Petraitis's study was most likely due to low predator density rather than a lack of generality of our earlier results. This reevaluation therefore suggests that within a broader conceptual framework, Petraitis' apparently divergent results are actually consistent with ours.     

Binding of polonium-210 to liver metallothionein

The interactions of 210Po at the molecular level in biological systems have received little study even though this alpha-emitting radionuclide occurs widely in nature. Polonium-210 was given subcutaneously to rats and found to be incorporated into liver metallothionein as judged by a number of criteria including heat stability, acetone precipitation, and chromatography. In vitro studies confirmed this binding. The binding of 210Po to metallothionein has implications that may help explain some of the radiation damage 210Po causes intracellularly.     

Studies on the genus Fontinalis (Musci: Fontinalaceae)

Fontinalis welchiana, a new species in the concave-leaved group ofFontinalis restricted to Arkansas, Missouri, and Illinois, differs fromF. novaeangliae by its slender size, dimorphic leaves, erect and strongly concave branch leaves, and lightly papillose exostome with ventral lamellae that are strongly rounded at the corners.Fontinalis allenii is a synonym ofF. antipyretica var.oreganensis.     

Spartina alterniflora loisel root structure and meiofaunal abundance

Meiofauna were collected from adjacent areas with and without Spartina alterniflora Loisel culms. Environmental complexity resulting from root structure cannot be determined by simply observing S. alterniflora culm distribution. There were no significant differences between the two areas with respect to root density or root sizes; however, the number of live roots was significantly higher in the area containing Spartina culms. Nematodes, the most abundant taxon were positively correlated with live root density. In contrast, the number of dead roots and harpacticoid copepods were higher in the area without culms. This study suggests that nematodes are positively associated with micro-oxygenated zones produced by live S. alterniflora roots. Other measures of biogenic structure, such as total root density or root size fractions are not important in affecting nematode abundance.     

Haemolysis of rabbit erythrocytes by a lectin from the seeds of<Emphasis Type="Italic">Croton tiglium</Emphasis>

The kinetics of haemolysis of rabbit erythrocytes byCroton tiglium lectin was studied as a function of concentration of the lectin and erythrocytes. The length of the prelytic period decreased with increasing lectin concentrations, indicating that the secondary events at the membrane which follow the binding of the lectin to cell surface carbohydrate receptors are accelerated at higher surface concentrations of the lectin. The rate or extent of haemolysis was not affected by the inclusion of ions like K⁺, Ca²⁺ and Mg²⁺ in the medium or by the substitution of ionic medium by a non-ionic medium. The inhibition of haemagglutination and haemolysis of rabbit red cells byCroton tiglium lectin by antilectin rabbit serum was observed. A possible mechanism of haemolysis by the lectin is discussed.