The physical state of alkali ions in a Halobacterium: some NMR results

The 46th case of known pregnancy-induced pancytopenia is reported. Pregnancy may play an etiologic role in this rare condition, but the specific mechanism is unknown. Maternal mortality is 63%, and fetal and neonatal wastage is 46%. The patient reported is a 24-year-old Oriental woman who delivered a healthy female infant. Her survival is attributed to conservative management with carefully timed packed cell and platelet transfusions.     

The state of ADP or ATP fixed to the mitochondria by bongkrekate

The reported studies are intended to clarify the binding state of ADP fixed to mitochondria under the influence of bongkrekate, and thus to discern between the affinity increase and reorientation mechanism proposed for the bongkrekate effect. (a) The composition of the intramitochondrial adenine nucleotide pool is not changed under the influence of bongkrekate with and without added nucleotides. (b) The added ADP and ATP fixed by bongkrekate can be identified as AMP, ADP and ATP in the same proportions as in the endogenous pool. (c) The bound nucleotides respond to oxidative phosphorylation or uncoupler stimulated dephosphorylation similar as endogenous nucleotides. It can be concluded that the ADP or ATP fixed under the influence of bongkrekate to the mitochondria are equilibrated with the intramitochondrial adenine nucleotide pool and are active in intramitochondrial phosphate transfer reactions. The results disagree with the affinity increase mechanism but support the reorientation mechanism which postulates that ADP and ATP are trapped in the mitochondria under the influence of bongkrekate in the same amount as there are carrier sites available outside before bongkrekate addition.     

The biological relevance of the binding of calcium ions by inositol phosphates

The binding of Ca2+ (chelation) by myo-inositol polyphosphates at pH 7.0 was studied using a Ca(2+)-sensitive electrode. Glucose 6-phosphate (used as a model for a monophosphate) bound Ca2+ with an affinity of 152 +/- 31 liters/mol and a molar ratio of 0.94 +/- 0.02. Inositol 3,4-bisphosphate, inositol 1,4,5-trisphosphate, inositol 1,3,4,5-tetrakisphosphate, and inositol hexakisphosphate showed affinities of 9.0 +/- 2.1 x 10(3), 6.3 +/- 1.5 x 10(3), 6.2 x 10(4), and 1.92 +/- 0.47 x 10(5) liters/mol, respectively, and molar ratios of 0.92 +/- 0.49, 0.95 +/- 0.10, 0.75, and 2.5 +/- 0.5. In general, the affinity increased with the number of phosphate substituents on the inositol ring, although the stereochemistry is also expected to be important. This suggests that for the physiologically relevant inositol phosphates (tris-, tetrakis-, pentakis-, and hexakis-) half-maximal Ca2+ binding will occur in the Ca2+ concentration range of approximately 5 x 10(-6) to 2 x 10(-4) M. This range lies between the basal intracellular and the fee extracellular Ca2+ levels (10(-7) and 10(-3) M), respectively, and may therefore be of physiological importance. Chelation provides a possible simple explanation for the inhibition by Ca2+ of inositol 1,4,5-trisphosphate binding to its receptor in rat cerebellum and other tissues. It may also have a role in limiting inositol phosphate-mediated increases in intracellular Ca2+.     

The design and evaluation of a step test for the rapid prediction of physical work capacity in an unsophisticated industrial work force

The influence of 100--600 microng of gamma-aminobutyric acid (GABA) injected into the right lateral ventricle of the brain on behavior and activity of the cerebral cholinergic system was studied in Wistar rats. Proportionally to dosage, GABA inhibited motor and exploratory activity in the rats. Reduction in the content of acetylcholine in the pons and medulla oblongata was accompanied by increased acetylcholinesterase (AChE) activity. GABA changed AChE activity differently in various parts of the brain. GABA depressed motor and exploratory activity in rats in a degree dependent on its dosage and inborn exploratory of the rats, and this effect was accompanied by changes in the cerebral cholinergic system.     

The state of psychological theory as illustrated by Melzack's new conceptual nervous system model/theory: Strong on imaginativeness but weak in inference.

Melzack's (see record 1989-30022-001) paper typifies the highly imaginative conceptual contributions that he has made in psychology. Moreover, as usual, there is close attention paid to applied relevance, rather than constraining his contribution to "ivory-tower," purely academic considerations. However, in my view, it is not at all clear that the New Conceptual Nervous System (NCNS) proposed by Melzack (1989, pp. 6-13) represents a genuine scientific advance in understanding and control. What is in doubt is whether there is any strong inference possible to ensure that changes in theoretical positions are due to evidential and logical considerations, rather than merely faddish ones. As I see it, there are at least three problems that tend to prevent such strong inference-based progress. The first problem is that Melzack follows the currently fashionable practice of using the terms "theory" and "model" (and, at times "approach") as if they were equivalent. The second problem is that although the central explanatory concepts of the new position are more complicated and imaginative than those of the old explanations, it is not clear that they are any less vague. The third problem is apparent from a consideration of the general structure of the paper with regard to the implications of the new CNS position. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The direct effect of heavy ions and electrons on thymidine in the solid state

PURPOSE: To study the direct effect of heavy ions and electrons on thymidine. MATERIALS AND METHODS: The thymidine samples in the solid state were exposed to a beam of O7+ heavy ions with an energy of 10.6 MeV/u (LET approximately 500keV/microm) and to electrons of 2MeV (LET approximately 0.18keV/microm). The major decomposition products of thymidine were purified by high performance liquid chromatography (HPLC) and identified by extensive spectrometric measurements (UV, mass spectroscopy, 1H and 13C NMR). RESULTS: The main degradation products of thymidine were isolated and characterized. Reaction mechanisms, involving transient radical species, are proposed to explain the heavy ion-mediated formation of the modified products. Furthermore, a semi-quantitative comparison of the modifications induced within thymidine by the two types of radiations was performed. CONCLUSION: Several new radiation-induced thymidine decomposition products have been isolated and characterized. The comparison of the effects induced by heavy ions and electrons on thymidine in the solid state clearly indicates several significant differences in the mechanisms of action. A relative increase in the extent of the modifications of the sugar moiety with respect to those of the base is observed with the heavy ions by comparison with electrons.     

Effects of physical training in a hypobaric chamber on the physical performance of competitive triathletes

The effects of training in a hypobaric chamber on aerobic metabolism were studied in five high performance triathletes. During 3 weeks, the subjects modified their usual training schedule (approximately 30 h a week), replacing three sessions of bicycling exercise by three sessions on a cycle ergometer in a hypobaric chamber simulating an altitude of 4,000 m (462 mm Hg). Prior to and after training in the hypobaric chamber the triathletes performed maximal and submaximal exercise in normoxia and hypoxia (462 mm g). Respiratory and cardiac parameters were recorded during exercise. Lactacidaemia was measured during maximal exercise. Blood samples were drawn once a week to monitor blood cell parameters and erythropoetin concentrations. Training in the hypobaric chamber had no effect on erythropoiesis, the concentrations of erythropoetin always remaining unchanged, and no effect on the maximal oxygen uptake (VO2max) and maximal aerobic capacity measured in normoxia or hypoxia. Submaximal performance increased by 34% during a submaximal exhausting exercise performed at a simulated altitude of 2,000 m. During a submaximal nonexhausting test, ventilation values tended to decrease for similar exercise intensities after training in hypoxia. The changes in these parameters and the improved performance found for submaximal exercise may have been the result of changes taking place in muscle tissue or the result of training the respiratory muscles.     

The role of performance antecedents and consequences in work motivation.

Assessed the effects of both antecedents and consequences while keeping supervisory involvement and stimulus changes constant. The safety performance of 200 employees in 4 departments of a processing plant was monitored 3 times/wk over 46 wks. A multiple baseline design was used in which the phases were introduced in steps. Following baseline, the antecedent condition was presented, in which safety rules were explained and safety meetings held, along with frequent supervisor interaction and stimulus changes. Then the performance consequence, feedback, in which a feedback graph was maintained and feedback meetings held, was added. The antecedent condition, even when bolstered by fairly extensive supervisor involvement, resulted in improvements in only 2 out of 4 departments. Only during the consequent condition did performance significantly improve in all departments over baseline and antecedent conditions. Furthermore, employees reported that they preferred obtaining information following their performance. The results confirm that performance consequences such as feedback play a critical role in work motivation and that antecedents alone may not be effective in all cases, even with fairly extensive supervisor involvement. (8 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fading and rebound of currents induced by ATP in PC12 cells

1. Patch clamp recording (whole cell configuration) was used to study the action of ATP on rat phaeochromocytoma (PC12) cells usually held at -70 mV and rapidly superfused with buffered saline. ATP (0.5, 1 or 5 mM), applied from micropipettes by pressure application with brief (< or = 50 ms) pulses, induced inward currents with rapid onset and decay. ADP and alpha, beta-methylene ATP were ineffective. 2. ATP (5 mM) applied with pulses > 200 ms long elicited a complex current response characterized by a rapid peak which faded and was followed by a strong current rebound (lasting several s) as soon as the application was terminated. This type of response was readily replicated as long as ATP applications were spaced at 2-3 min intervals. The amplitude of peak and rebound currents was dependent on the length of pressure pulse and was similarly depressed by bath application of a threshold dose (25 microM) of ATP. Rapid fading and rebound of ATP-induced membrane currents were also observed when the Y-tube method was used for applying this agonist. 3. The reversal potential for peak and rebound currents was the same while the time constant values for peak fading and rebound onset were insensitive to changes in membrane potential between -70 and -40 mV. When ATP was applied to a cell clamped at depolarized potential, no current was observed but rapid return of the membrane potential to -70 mV immediately at the end of ATP application was associated with a large rebound current. 4. Brief (20 ms) application of ATP during the onset of the rebound current strongly and transiently suppressed it. The same application performed during the gradual decay of the rebound wave elicited a transient inward current which was much smaller and shorter than the one observed when the cell was in its resting state. Application of 2 s ATP pulses at 20 s intervals equally reduced the initial peak and rebound currents which recovered at the same rate. 5. The present data are interpreted according to a scheme which suggests two types of ATP receptor desensitization. The first one (D1) would be characterized by fast kinetics and low agonist affinity; rapid recovery from D1 would then be manifested as current rebound presumably due to receptor reactivation. The second desensitized state (D2) has slow kinetics and high affinity for the agonist: it is therefore typically seen with sustained application of a low dose of ATP. It is proposed that desensitization and its recovery can influence the time course of membrane responses mediated by purinoceptors.     

The dependence on the extramitochondrial ATP/ADP-ratio of the oxidative phosphorylation in mitochondria isolated by a new procedure from rat skeletal muscle

A simple method for preparation of rat skeletal muscle mitochondria is presented using gentle mechanical homogenization in a syringe and nagarse treatment (EC 3.4.4.16). This method enables the preparation of skeletal muscle mitochondria, whose outer membrane is intact to 95%. Furthermore, with mitochondria prepared by this method the regulation of respiration and phosphorylation by the extramitochondrial ATP/ADP-ratio can be demonstrated. In accordance to rat liver and heart mitochondria and to mitochondria of rabbit reticulocytes, the regulation by the extramitochondrial ATP/ADP-ratio lies in the range from 5 (corresponding to 98% of the maximum respiration) to 100 (corresponding to state 4). At extramitochondrial ATP/ADP-ratios from 0.01 to 1 the respiration rate is nearly constant (maximum rate of respiration).     

Human problem solving: The state of the theory in 1970.

Summarizes research of the past 15 yr. directed toward discovering and explicating the organization of information processes that underlies human problem solving. The basic characteristics of the human information processing system (IPS) serial processing, small short-term memory, infinite long-term memory with fast retrieval but slow storage impose strong conditions on the ways in which the system can seek solutions to problems in large problem spaces. The current theory is described in 4 broad propositions: (a) a few gross characteristics of the human IPS are invariant over task and problem solver; (b) these characteristics determine that a task environment is represented (in the IPS) as a problem space, and that problem solving takes place in a problem space; (c) the structure of the task environment determines the possible structures of the problem space; and (d) the structure of the problem space determines the possible programs that can be used for problem solving. These propositions and their relation to the known characteristics of the IPS are developed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The importance of physical fitness in the performance of adequate cardiopulmonary resuscitation

Trehalose is a saccharide that possesses no reducing group and so has possible use in parenteral nutrition, especially because it can be stored with amino acids without undergoing the Maillard reaction. To evaluate this possibility, a series of experiments were conducted. The activity of trehalase, an enzyme that metabolizes trehalose to glucose, was measured in rabbit serum and kidney. Conversion of trehalose to glucose and excretion of trehalose in the urine were measured in rabbits administered 10% trehalose intravenously. The effects on nutritional indices as indicators of its use as an energy source were also measured in rabbits infused with 8.23 g.kg-1.d-1 (4. 12 g.kg-1 on d 1) of trehalose for 5 d. Trehalase activity resembled maltase activity, both being high in the renal cortex (2.04 +/- 0.71 and 2.93 +/- 0.26 micromol.g-1.min-1, respectively), weak in the medulla, and undetectable in the serum. Serum glucose and insulin concentrations were increased significantly by trehalose infusion. Significant elevations were observed in serum glucose but not insulin levels by maltose infusion. On the other hand, urinary excretion of trehalose (1.1 +/- 2.1% of dose) was significantly lower than that of maltose (10.1 +/- 4.9% of dose). Similar effects of trehalose and maltose infusions as seen in normal rabbits occurred in rabbits with alloxan diabetes (urinary excretion rate, 3. 8 +/- 3.0% of the infused trehalose dose and 35.6 +/- 9.7% of the infused maltose dose). Nitrogen balance was positive in the trehalose- and glucose-infused normal rabbits with significant difference from the control group infused with saline, suggesting that trehalose was used as an energy source. These results suggest that trehalose has the potential for use as a saccharide source for parenteral nutrition.     

That "vision thing": The state of theory in social and personality psychology at the edge of the new millennium.

Social psychology's status as a theoretical discipline is assessed. Whereas it has excelled as an experimental science, the field has generally eschewed broad theorizing and tended to limit its conceptualizations to relatively narrow, "mid-range" notions closely linked to the operational level of analysis. Such "theory shyness" may have spawned several negative consequences, including the tendency to invent new names for old concepts, fragmentation of the field, and isolation from the general cultural dialogue. Recently, steps have been taken to encourage greater theoretical activity by social psychologists, and there are now several major outlets for theoretical contributions. Further initiatives are needed, however, to instigate theoretical creativity, including ways of overcoming disciplinary risk aversion and the training of young social psychologists in ways and means of theory construction. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

The physical state of nafcillin sodium in frozen aqueous solutions and freeze-dried powders

The purpose of this study was to develop a better understanding of the physical chemistry of freeze drying of lyotropic liquid crystals using nafcillin sodium as a model solute. Solutions and freeze-dried powders of nafcillin sodium were studied by polarized light microscopy, differential scanning calorimetry, x-ray powder diffraction, and water vapor adsorption. Differential scanning calorimetry thermograms of nafcillin sodium solutions contain a melting endotherm at approximately -5.5 degrees C and, depending on the concentration and heating rate, a crystallization exotherm immediately after this endotherm followed by the melting endotherm of ice. When the sample is annealed at -4 degrees C, both the endotherm and exotherm are eliminated, and a new endotherm appears at approximately -1 degree C on the shoulder of the ice-melting endotherm. The data are interpreted as melting of a liquid crystalline phase, followed by crystallization. X-ray powder diffractograms of unannealed freeze-dried nafcillin sodium are consistent with a lamellar liquid crystal. Diffractograms of annealed freeze-dried nafcillin sodium indicate crystalline material which is a different crystal form than the monohydrate starting material. Moisture adsorption isotherms of the freeze-dried annealed (crystalline) and unannealed (liquid crystalline) nafcillin sodium show different affinities for moisture compared to the crystalline starting material. Solid-state stability data demonstrate that the freeze-dried liquid crystalline form of nafcillin sodium is much less stable than the freeze-dried crystal-line material. The literature recognizes two types of solute behavior on freezing, where the solute either crystallizes from the freeze concentrate or remains amorphous. Lyotropic liquid crystal formation during freezing represents a separate category of freezing behavior, the physical chemistry of which is worthy of further investigation.     

Determination of the physical state of drug in microcapsule and microsphere formulations

Tolnaftate microcapsules and microspheres were prepared by gelatin-acacia coacervation and emulsion-solvent evaporation methods respectively. The physical state of the drug in these formulations was determined by using scanning electron microscopy (SEM), X-ray powder diffractometry, and differential scanning calorimetry (DSC). High pressure liquid chromatographic (HPLC) method was used for stability determination and polymer-drug interactions were evaluated using FTIR. The pros and cons of each method, in the assessment of the physical state of drug in these formulations, were investigated. SEM was found to be useful in obtaining a direct visual evidence of the presence of crystalline drug in the microspheres, but not for the microcapsule formulation. The DSC method was used to determine the physical state of the drug qualitatively in both these formulations. In the case of the microcapsules, accurate quantitation of the crystalline drug content by DSC was not possible because of the interference of thermal events. Powder X-ray diffractometric method was able to demonstrate the presence of crystalline drug and polymorphic changes, if any, in both these formulations. HPLC data revealed that the drug was stable in these formulations for at least 6 months. The FTIR studies indicated the absence of any drug interaction with the polymeric matrix materials, during preparation of these dosage forms.     

Smoking as a moderator of the relationship between affective state and absence from work.

192 female student nurses from 2 hospitals were administered the Middlesex Hospital Questionnaire and a measure of smoking behavior. Sickness and absence data were taken from Ss' training records. Prior to exposure to the work situation, levels of affective distress did not differ significantly between groups differing in smoking behavior (nonsmoker, relaxation smokers, and stress smokers). Multiple regression analysis showed overall significant differences in absence frequency between hospitals and between smokers and nonsmokers. There was also a significant interaction between smoking behavior and affective state; only among the stress smokers did initial level of affective distress predict frequency of absence. Thus, the present study (conducted in a setting that did not permit smoking during working hours), showed that withdrawal from work in direct relation to affective symptom levels occurred only among Ss who habitually smoked in response to stress. (56 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Maintenance of ions, proteins and water in lens fiber cells before and after treatment with non-ionic detergents

The proportional odds model is illustrated in the analysis of two efficacy scales used in a phase II clinical trial involving 81 schizophrenic patients. The proportional odds model preserves the discrete, ordinal nature of one of the scales. The analysis of this data suggested that the relationship between the two scales is not captured by a linear proportional odds model. A linear model and a piecewise linear model for the explanatory variable were therefore compared using likelihood-based analyses. Residuals from both models were compared. Predicted probabilities for the ordinal categories were constructed from the estimated model. Extensions and limitations of the model for interpretation of other trials and for the planning of future trials are discussed.