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Our experience with a U-intoxicated patient and human data in the literature suggest the kidney U burden should not be allowed to exceed 0.26 micrograms g-1. The Annual Limit on Intake (ALI) for natural U was calculated from the chemical toxicity of U and was found to be lower than that reported previously.
OBJECTIVES: We investigated the influence of the narcotic anesthetic remifentanil on irreversible myocardial ischemic injury. METHODS: New Zealand White rabbits were anesthetized with propofol (0.7-1.8 mg.kg.min) and then subjected to 30 min regional myocardial ischemia and 3 h reperfusion (CON). Some animals also underwent ischemic preconditioning, elicited by either one (IP1) or two (IP2) cycles of 5 min ischemia and 5 min reperfusion, and/or remifentanil, administered either as a transient infusion mimicking the preconditioning protocol (RP2, 10 microg x kg x min) or as a continuous infusion (R, 3-10 microg x kg x min). Rabbits were randomly assigned to experimental groups. Infarct size was assessed with tetrazolium. Results are reported as mean+/-SD. RESULTS: Non-preconditioned infarct size was approximately 50% of the area-at-risk (49.6+/-20.1% CON). Both one and two cycles of ischemic preconditioning markedly reduced infarct size (49.6+/-20.1% CON versus 18.6+/-8.6% IP and versus 7.5+/-7.6% IP2; both p<0.001). Preconditioning with remifentanil modestly reduced infarct size (49.6+/-20.1% CON versus 29.3+/-8.5% RP2; p<0.01). However, sustained administration of remifentanil did not provide protection (49.6+/-20.1% CON versus 43.9+/-16.2% R), and it attenuated the protection offered by preconditioning (49.6+/-20.1% CON versus 35.6+/-20.7% R+IP1, p=NS; and versus 14.5+/-14.5% R+IP2; p<0.05). CONCLUSION: Transient pre-ischemic administration of remifentanil modestly reduces infarct size in propofol-anesthetized rabbits, but continuous administration of remifentanil increases the threshold for ischemic preconditioning-induced infarct limitation.
We present the results of a detailed many-multiplet analysis performed on a new sample of Mg ii systems observed in high quality quasar spectra obtained using the Very Large Telescope. The weighted mean value of the variation in alpha derived from our analysis over the redshift range 0.4</=z</=2.3 is Deltaalpha/alpha=(-0.06+/-0.06)x10(-5). The median redshift of our sample (z approximately 1.55) corresponds to a look-back time of 9.7 Gyr in the most favored cosmological model today. This gives a 3sigma limit, -2.5 x 10(-16)</=(Deltaalpha/alphaDeltat)</=+1.2 x 10(-16) yr(-1), for the time variation of alpha, that forms the strongest constraint obtained based on high redshift quasar absorption line systems.
The occurrence of O(2)-insensitive photosynthesis at high quantum flux and moderate temperature in Spinacia oleracea was characterized by analytical gas exchange measurements on intact leaves. In addition photosynthetic metabolite pools were measured in leaves which had been rapidly frozen under defined gas conditions. Upon switching to low O(2) in O(2)-insensitive conditions the ATP/ADP ratio fell dramatically within one minute. The P-glycerate pool increased over the same time. Ribulose bisphosphate initially declined, then increased and exceeded the pool size measured in air. The pools of hexose monophosphates and UDPglucose were higher at a partial pressure of O(2) of 21 millibars than at 210 millibars. These results are consistent with the hypothesis that the rate of sucrose synthesis limited the overall rate of assimilation under O(2)-insensitive conditions.
Earlier work (SE Taylor, N Terry [1984] Plant Physiol 75: 82-86) has shown that the rate of photosynthesis may be colimited by photosynthetic electron transport capacity, even at low intercellular CO(2) concentrations. Here we monitored leaf metabolites diurnally and the activities of key Calvin cycle enzymes in the leaves of three treatment groups of sugar beet (Beta vulgaris L.) plants representing three different in vivo photochemical capacities, i.e. Fe-sufficient (control) plants, moderately Fe-deficient, and severely Fe-deficient plants. The results show that the decrease in photosynthesis with Fe deficiency mediated reduction in photochemical capacity was through a reduction in ribulose 1,5-bisphosphate (RuBP) regeneration and not through a decrease in ribulose 1,5-bisphosphate carboxylase/oxygenase activity. Based on measurements of ATP and NADPH and triose phosphate/3-phosphoglycerate ratios in leaves, there was little evidence that photosynthesis and RuBP regeneration in Fe-deficient leaves were limited directly by the supply of ATP and NADPH. It appeared more likely that photochemical capacity influenced RuBP regeneration through modulation of enzymes in the photosynthetic carbon reduction cycle between fructose-6-phosphate and RuBP; in particular, the initial activity of ribulose-5-phosphate kinase was strongly diminished by Fe deficiency. Starch and sucrose levels changed independently of one another to some extent during the diurnal period (both increasing in the day and decreasing at night) but the average rates of starch or sucrose accumulation over the light period were each proportional to photochemical capacity and photosynthetic rate.
Perceived risk and related attitudes have been implicated as major factors in many of the difficult policy problems that face modern society (nuclear power, genetically modified food, etc). Experts often argue that no or very small risks are involved; people are still worried. Why? The standard answer is lack of trust. Data on trust and risk perception, however, point to only a weak relationship between the two (r approximately 0.3). It is suggested here that the reason for the surprisingly minor importance of trust is that people believe that there are clear limits to how much science and experts know. Results are presented from studies of risk perception of the public, experts, and politicians. Politicians and members of the public believe that there are many unknown effects of technology and such beliefs were strongly related to their perceived risk. Experts on nuclear waste, on the other hand, seemed to believe that little is unknown in their field of expertise. Regression analyses of risk perception showed the unknown-effects factor to be a more important explanatory factor than trust for the public and politicians.
An unusual pedigree of female-limited seizures with or without mental retardation is updated. The disorder was first detected in a large cohort of women whose fathers were brothers, and affected women had previously transmitted the disorder. Four brothers of affected females have now had five unaffected daughters while four affected women have had four affected and one unaffected daughters and two unaffected sons. This unusual transmission pattern is discussed in terms of germ-line imprinting, neuronal sexual differentiation, and the generally higher risk of seizures seen when the mother, rather than the father, is affected.
The bacterium Xanthomonas campestris, which synthesizes the commercially important polysaccharide xanthan, was grown aseptically in 1.2 L fermenters using semicontinuous cell culture technique (d' = 0.0035 h-1). The effects of carbon-substrate concentration on xanthan production were investigated at three initial glucose concentrations (Go = 15, 20, 25 g/L). Cell biomass synthesis was nitrogen-limited by use of a chemically defined medium that contained NH3-N as the sole nitrogen source at a concentration where it was exhausted before glucose. A linear relationship between biomass synthesis and NH3-N depletion was observed. This relationship remained valid only until NH3-N exhaustion, after which biomass concentration slowly rose another 20 percent before declining. Another linear relationship was found between xanthan synthesis and glucose uptake. This relationship was unaffected by the disappearance of NH3-N and held through glucose exhaustion. The quasi-stoichiometric yield coefficients obtained for each linear relationship were not affected by G0-. Biomass synthesis kinetics showed no variation with G0 before NH3-N exhaustion; afterwards, cell biomass decline was delayed by increasing G0. Xanthan synthesis kinetics displayed no detectable response to depletion of NH3-N and plateauing of biomass concentration; however, there was a marked slow down in the net rate of xanthan synthesis and a drop in xanthan yield after cell biomass decline became noticeable.
During the first month after the limited National Health Service drug list came into effect 17 cooperative general practitioners recorded the actions taken when a now prohibited drug would formerly have been prescribed. An average of 6% of direct surgery contacts with patients and 8% of indirect contacts with patients were affected by the new regulations, but in 2% and 4% of cases respectively the patient received the same pharmacological substance under a different (generic or approved) name. Where a real change in pharmacological constitution or formulation had been required four fifths of these substitutes were considered by the doctors to result in less effective treatment. In 1% of contacts no drug was issued or recommended where one would formerly have been given.
This notice sets forth a revised schedule of limits on skilled nursing facility inpatient routine service costs that are paid for under Medicare. This schedule applies to cost reporting periods beginning on or after October 1, 1987.
The productivity of lettuce in a combination of high light, high temperature, and elevated CO2 has not been commonly studied because rapid growth usually causes a calcium deficiency in meristems called tipburn, which greatly reduces quality and marketability. We eliminated tipburn by blowing air directly onto the meristem, which allowed us to increase the photosynthetic photon flux (PPF) to 1000 micromoles m-2 s-1 (57.6 mol m-2 d-1); two to three times higher than normally used for lettuce. Eliminating tipburn doubled edible yield at the highest PPF level. In addition to high PPF, CO2 was elevated to 1200 micromoles m-2 mol-1, which increased the temperature optimum from 25 to 30 degrees C. The higher temperature increased leaf expansion rate, which improved radiation capture and more than doubled yield. Photosynthetic efficiency, measured as canopy quantum yield in a whole-plant gas exchange system, steadily increased up to the highest temperature of 32 degrees C in high CO2. The highest productivity was 19 g m-2 d-1 of dry biomass (380 g d-1 fresh mass) averaged over the 23 days the plants received light. Without the limitation of tipburn, the combination of high PPF, high temperature, and elevated CO2 resulted in a 4-fold increase in growth rate over productivity in conventional environments.
For demonstrating ultrastructurally the distribution of anionic sites (AS) in the inner limiting membrane (ILM) of the rabbit's retina, the immersion method with cationic tracer, polyethyleneimine (PEI) was applied. This method was found to be simple and useful for the observation of AS in the ILM. In the posterior pole of the eyeball (visual streak and medullary ray), PEI particles were arranged evenly in the lamina rara (LR) of the ILM. The mean diameter of PEI particles was 20 nm, and intervals between them (40-50 nm) were the same as those of fine strands in the LR. However, the peripheral retina, the distribution of PEI particles were sparse and random, while in the lamina densa (LD) of each ILM, PEI particles were absent. AS stained with PEI were present in the residual vitreous fibers. These results may provide the morphological basis for the theory that AS of the ILM act as a charge barrier between the retina and the vitreous cavity.
In order to clarify the ultrastructural details, electron microscopic observations of the inner limiting membrane (ILM), critical point drying and surface replication methods with collagenase digestion were performed on rabbit's ILM. The results were as follows,: 1) This method was simple, the electron microscopic image is highly reproducible and a bird's-eye view of the ILM is possible. 2) The ILM was composed of a fine three-dimensional meshwork structure with numerous pores (sieves). 3) The diameter of the pores varied from 10 to 25nm. Mean diameter of the pores is 13.43nm in the visual streak, 13.59nm in the medullary ray, 13.40nm in the peripheral retina, and there were no statistical differences among these three regions. 4) In the peripheral retina, it was difficult to observe the ILM because vitreous fibrils lay densely on it. The pore's shape in the peripheral retina was different from that in the posterior pole retina. These results may provide the morphological basis for the theory that the pores of the ILM act as the main filtration barrier between the retina and the vitreous cavity. It is supposed that the bulk of substances are transported from the retina mainly through the ILM of the posterior pole, because dense vitreous fibrils of the peripheral retina disturb that transport.
Previous studies in which an alloantiserum was used to measure Slp levels indicated that in certain inbred strains of mice (Slpa), this protein was sex-limited, that is, present only in males. We raised several monoclonal antibodies directed against different epitopes of Slp and used them to develop a sensitive two-site immunoradiometric assay. Using this assay we detected Slp in serum of all Slpa females previously thought to be phenotypically negative. The levels of Slp in these females are about 0.2 to 4% of that of the males of the same inbred strain. The molecule found in serum of females was isolated by affinity chromatography and was found to have the characteristic three-chain structure of male Slp. These findings establish that the presence of Slp in Slpa females is the rule rather than the exception. Quantitative differences similar in magnitude to those found between males and females were also detected among Slpa males; i.e., Sd males have about 100 times more Slp than Sp males. The mechanisms by which androgens determine the extensive quantitative male-female differences, and by which the S region determines large variations among Slpa males, are unknown.
The Limited Spearman-Karber Procedure (LSKP) and Stumbo Murphy and Cochran Procedure (SMCP) are procedures to determine D-value in the Most Probable Number method (MPN). International Organization for Standardization (ISO)/Technical Committee 198/Working Group 4 contributing for the preparation of documents on biological indicator has adopted only LSKP in MPN. SMCP has been rejected due to the reason of inaccuracy without any scientific proof. Therefore, in order to confirm whether this is scientifically correct or not, Japanese delegates decide to compare both methods in simulation and experimental procedures using biological indicator and biological indicator evaluator resistometer. The result indicated that SMCP with some restrictions was not always inferior to LSKP and gave identical results.
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