The influence of aggregate size and drannage potential on germination of barley seeds in flooded soil

Emergence and growth of barley was severely decreased by short periods (less than 24 hours) of pre-emergence waterlogging at 20°C. The extent of damage depended on a combination of duration of waterlogging, soil water potential and aggregate size. Potentials of less than—4kPa prevented loss of plants developing in aggregates of less than 2 mm diameter after a transitory period of waterlogging although some shoot and root damage occurred. By comparison seeds growing in soil consisting of aggregates greater than 2 mm in diameter were not damaged by transitory waterlogging even when drainage only occurred at−0.8kPa. The severity of damage increased with the period of waterlogging. A criterion obtained as the product of mean size grade and water potential gave a single value (−4NM⁻¹) below which emergence was satisfactory. Waterlogging halfway through germination gave more severe damage than near sowing date or near emergence.     

Ice Encasement Injury to Microsomal Membranes from Winter Wheat Crowns : I. Comparison of Membrane Properties after Lethal Ice Encasement and during a Post-Thaw Period

The functional and physical properties of cellular membranes isolated from Triticum aestivum, cvs Norstar and Fredrick, were altered coincident with changes in composition after a lethal ice-encasement stress and further during a 6 hour post-thaw period. Crowns encased in ice for a duration which inhibited regrowth, exhibited enhanced rates of electrolyte leakage. Furthermore, the recovery of total microsomal protein and phospholipid declined, suggesting that some membrane degradation had been induced during the anoxic stress. The microviscosity of microsomes and liposomes prepared from such membranes increased during stress, and this was correlated with a 2- to 4-fold increase in the free fatty acid levels in the microsomal fraction. There was, however, only a relatively minor change in fatty acid unsaturation during the ice-encasement stress. The process continued during a 6 hour aerobic post-thaw treatment, but the pattern was somewhat different. During this phase, the leakage of electrolytes was further increased and the recovery of microsomal protein and phospholipid continued to decline, indicating general degradation; but, in contrast to the anoxic phase, the degree of fatty acid unsaturation declined markedly, indicating lipid peroxidation.     

Hynes pharyngoplasty revisited

The treatment of velopharyngeal incompetence remains unsatisfactory because the causes are many, as are the variations in anatomic and physiologic defects. Therefore, full assessment and investigation are essential in tailoring the surgery to the defect. A modified Hynes pharyngoplasty has been used in 40 patients, aged 4 to 52, over a 4-year period for velopharyngeal incompetence of varying etiologic causes. Speech was assessed before and at least 6 months after pharyngoplasty. At the same time, radiologic and, when possible, nasendoscopic investigations were undertaken. Thirty-eight patients had no or variable nasal escape (variable defined as achieving intermittent closure), whereas 33 had normal or slight hyponasal resonance. There was only one complication, an asymptomatic dehiscence of the "bucket handle" flap from the posterior wall. Thirteen patients had an assortment of side effects, none requiring surgical treatment. We believe that patients who are suitable for the described sphincter pharyngoplasty are those with slight or moderate nasal escape having a mobile palate with an anteroposterior gap of 5 mm or less.     

The effects of ionizing radiation on the pulmonary vasculature of intact rats and isolated pulmonary endothelium

We studied the effects of ionizing radiation on the morphology of the pulmonary circulation using an in vivo rat model and an in vitro pulmonary artery endothelial cell model. Gamma radiation was given as either an acute (30 Gy) or fractionated (5 X 6 Gy) dose to one hemithorax of rats. An acute 30-Gy dose delivered resulted in a 70% decrease in pulmonary arterial perfusion, using technetium-99m microaggregated albumin (99mTc-MAA), in the irradiated lung by 2-3 weeks after irradiation. Pulmonary microradiographs, using a barium sulfate perfusion method, obtained 2-3 weeks after irradiation demonstrated widespread loss of capillary filling and segmentation of the vessels. Histologic examination demonstrated intact capillaries, suggesting that the alterations in pulmonary perfusion were at the precapillary level. Similar abnormalities in lung perfusion and morphology were found after delivery of fractionated doses of radiation, but the onset of the changes was delayed, occurring 4-6 weeks postirradiation. Using cultured pulmonary endothelial cell monolayers, cell sloughing and retraction from the surface substrate were observed within 24 h after in vitro delivery of 30 Gy. Similar findings occurred in monolayers given fractionated doses (5 X 6 Gy) of radiation 2-3 days after the final dose. The in vivo animal and in vitro endothelial cell models offer a useful means of examining the morphologic alterations involved in radiation lung vascular damage.     

Catecholamine content and acetylcholinesterase activity in the brain of rats exposed to lasers

The catecholamine content was quantitated and acetylcholinesterase activity determined in rat brain locally exposed to laser radiation. It was shown that the adrenaline/noradrenaline ratio changed in the tissues under study and the cholinergic system was involved in the abscopal effect of laser radiation.     

Relative biological effectiveness (RBE) of neutrons produced by 50 MeV deuterons and by 34, 45, 65 and 75 MeV protons

RBE of p(34) + Be, p(45) + Be, p(65), + Be, p(75) + Be and d(50) + Be neutron beams produced at the cyclotron "Cyclone" of Louvain-la-Neuve were measured. The biological criterion was the regeneration of the crypts of the intestinal mucosa (50 regenerated crypts per circumference) after abdominal irradiation in mice. Taking the p(65) + Be neutrons as reference, RBE values were found equal to 1.12, 1.07, 1.00 (Ref.), 0.96 and 1.02 respectively. These results are consistent with those published for cell lethality in vitro. However, the RBE variation is smaller than this previously obtained in the laboratory for growth inhibition in Vicia faba.     

Aspirin and acetaminophen use by pregnant women and subsequent child IQ and attention decrements

In a longitudinal prospective study of 1,529 women pregnant in 1974-1975, aspirin and acetaminophen were the two medications most frequently taken during the first half of pregnancy (46 and 41%, respectively). In a selected cohort of 421 offspring of these women, examined at 4 years of age, maternal aspirin use during the first half of pregnancy was significantly related to IQ and attention decrements in the exposed children. Multiple regression analyses were used to statistically adjust for a variety of potentially confounding factors including demographic characteristics, child characteristics, other exposures, and lifestyle/environmental variables. Continuous dose-response and step-function parameterizations of aspirin exposure were both statistically significant and not clearly distinguishable from each other. The estimated aspirin effect is significantly greater for girls than boys. Aspirin effects on offspring function were found in the absence of effects on physical size both at birth and at 4 years. Maternal acetaminophen use was not significantly related to child IQ or attention. As this exploratory research originated from observations of a data set gathered for other purposes, it would be desirable to have these findings replicated in other studies. Further follow-up of the children at a later age is planned.     

Potential long-acting contraceptive agents: esters of testosterone with alkoxy- and halogeno-substituted carboxylic acids

The chemical synthesis and physical data of several new esters of testosterone (17 beta-hydroxyandrost-4-en-3-one), which contain either a halogeno or an alkoxy substituent in the acid chain, are reported.