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Recent recommendations for educational reform at the elementary level are considered in terms of their implications for improving the self-directed learning capabilities of students. The construct of self-directed learning is defined and its importance at the elementary level is explored. The article focuses on the ways by which classroom practices and conditions can encourage or discourage capabilities and dispositions to engage in self-directed learning. A classroom environment that would support effective self-directed learning is described with respect to 4 components: demands, supports, opportunity, and goal structure. Examples of how classroom tasks might be defined or changed are included within the discussion of each component.

The aqueous high pressure–temperature oxidation of cyclohexanone was found to be strongly catalyzed by silver, iron(III), and copper ions but not by aluminum, cobalt, manganese(II), or nickel ions. The reactivities of the catalytic ions were inhibited by the acidic oxidation products. Accordingly, initial reaction velocities were determined and used to correlate the kinetic data. A detailed kinetic study of copper ion catalysis has shown that in the presence of that ion the reaction was first order in cyclohexanone, one-half order in copper ion, and zero order in oxygen. The rate of enolization of cyclohexanone appeared to be unaffected by the presence of copper ion under conditions of constant acidity but was strongly catalyzed by both deuterium ion and acetate ion. Further, the rate of oxidation exceeded the rate of enolization at higher copper ion concentrations. These data contrast with the uncatalyzed oxidation, for which the kinetic reaction was first order in cyclohexanone, one-half order in oxygen, and the rate of oxidation was much less than the rate of enolization. The activation energies for the catalyzed and uncatalyzed oxidations were about the same, but the entropies of activation were quite different. From these data it is concluded that the enol is not a major intermediate for the catalyzed reaction. It is suggested that the copper ion may form an active peroxy complex with the oxygen molecule to serve as the reactive oxidant. Keywords: metal ion catalysis, kinetics, cyclohexanone, high temperature oxidation, high pressure oxidation.

The application of the elegant Fourier transform method of Smith et al. 3,4 to measurements on ultrathin, “black” lipid membrane is described. A digital computer generates a waveform containing many frequencies, applies it to the measurement cell containing an artificial, ultrathin membrane, collects the resulting electrical response, extracts the cell admittance by a substitution method, and facilitates subsequent numerical data analysis. The performance of the instrument is illustrated.

Intraaortic balloon counterpulsation (IABP) has become an accepted modal ity to assist the failing heart. An eleven-year experience in 637 patients with this modality was reviewed. Vascular complications occurred in 66 (10.4%). Female patients made up 27% of all IABP patients and 29 of the 66 IABP patients (44%) with vascular complications. Vascular complications were four times more frequent when IABP was accomplished percutaneously as contrasted with the use of a sidearm graft. The factors that predispose patients to vascular complications with IABP, the measures to decrease the incidence of these complications, and the manage ment of these complications to minimize loss of limb and/or life are discussed.

Students' reported total study time, their allocation of that time to specific study activities, and relationships between such allocations and achievement were examined across three grade levels, junior high, senior high, and college. Whereas reported total study time measures differed significantly across grade levels and among courses within levels, correlations of the total time indices with achievement did not differ significantly from zero. The allocation of time to specific study activities also varied across grade levels, as did correlations between these specific activities and achievement. The grade-level results, however, were not representative of particular courses within grade levels. These within-grade differences were not accountable in terms of corresponding differences in course demands.

Glutaminase mRNA levels increased over 3-fold relative to total RNA, poly(A)+ RNA, and beta-actin mRNA in neonatal rat cerebellar granule cells as the cells differentiated between days 3 and 8 in culture. In contrast, mRNA levels of another glutamate cycle enzyme, glutamine synthetase, remained constant. Glutaminase protein levels increased per cell more than 2-fold between days 3 and 8, and at least 3-fold by day 10 in these cells. The total amount of glutamate per cell increased about 40% during this period. Glutaminase induction paralleled the development of Ca2+-dependent glutamate release, and the formation of neurites, synaptic vesicles, and synapses. The induction of glutaminase in developing granule cells is consistent with a special role for glutaminase in the synthesis of neurotransmitter glutamate.

After introducing the larger investigation of which the present paper is a part, this paper reports on the development and application of a framework for assessing course characteristics. The framework distinguishes three types of features: apparent demands (five cognitive and two self-management), net demands adjusted for supports (four cognitive and one self-management), and net demands adjusted for compensations (one cognitive and one self-management). Course profiles, assessed by classroom observations and analyses of all course documents, of 11 junior high school, 9 senior high school, and 2 college social science courses are reported and discussed. Findings include: (1) complex patterns of variation across educational levels in the profiles of apparent and net demands for each of the types of demand assessed; and (2) wide ranges within educational levels in the magnitude of each of these features. Discussion focuses on the utility of the framework for (1) predicting variance in students' performances and (2) constructing, evaluating, and revising curriculum.

The film badge is the device used most frequently today for monitoring the radiation exposure of personnel. In spite of many advantages, it has numerous limitations in practical use. Many reports in the literature are concerned with the problems and inadequacies of film badge dosimetry (1-11). One source of difficulty lies in the attempt to relate the “dose” received by the film to the “dose” received by the individual who may have worn the film badge; “personnel exposure” cannot be equated to “film-badge exposure” without knowledge of the pertinent factors involved in the specific exposure situation. The degree of accuracy that may be practically obtained by film-badge dosimetry, however, is basic to any reliable estimate derived therefrom of personnel exposure. With the exception of large AEC contractors, hospitals and other institutions as well usually rely upon commercial suppliers for film-badge dosimetry service. This paper is concerned with the reliability that may be expected of commercial film-ba...

Tucker, Fayne L. (University of Southern California, Los Angeles), John W. Thomas, Milo D. Appleman, Stewart H. Goodman, and Jerry Donohue. X-ray diffraction studies on metal deposition in group D streptococci. J. Bacteriol. 92:1311-1314. 1966.-Streptococcus faecalis N83 and S. faecium K6A reduced several compounds of Group VI elements to the elemental form, but reduced none of several compounds tested containing elements of other groups. The elemental tellurium deposited by S. faecium K6A was in general of a larger particle size than that deposited by S. faecalis N83 as judged from X-ray diffraction analysis. The particle size of the deposited tellurium was correlated with the blackness of the precipitate produced by cells growing in the presence of tellurite. A black and gray variation was observed in S. faecium K6A which was considered to be due to particle size, the amount of tellurium present, and the location of the deposited tellurium. The gray color of S. faecium K6A was not due to the presence of any oxidized tellurium products.

Eighty elementary school children completed an intentional and an incidental associative learning task. Each of three groups stratified on intelligence and creativity made either humorous, unusual, or usual associations among common objects. Intentional learning, only, differentiated IQ groups (p

The rate of enolization and acetone has been determined as 6.6 × 10−4 s−1 at 193.5 °C under nitrogen at 136 atm total pressure via isotopic exchange. The rate of oxidation was determined to be 8.8 × 10−6 s−1 at 193.5 °C in 123 atm partial pressure of oxygen (136 atm total pressure). In a previous study it was shown that the rates of oxidation of several ketones correlated with the extents of enolization at room temperature. This prompted the suggestion that the enol is an intermediate in the oxidation. Since the rate of enolization exceeded the rate of oxidation by a factor of 75, this suggestion is further supported. A dependence of the rate of oxidation of acetone on oxygen concentration was also demonstrated.

The use of silastic catheters for total parenteral nutrition has greatly expanded. Their decided advantages of flexibility and minimal thrombogenicity favor their use in the long-term nutritional support. This case report details the development of central vein thrombophlebitis associated with an indwelling central silastic catheter. This uncommon hazard of central venous catheterization is not eliminated by the use of silastic catheters.

This study reviews the experience in a community hospital with aortocoronary bypass in 100 consecutive patients following failed percutaneous transluminal coronary angioplasty (PTCA) in terms of timing of intervention, morbidity, and mortality. Patients undergoing operation within 24 hours of PTCA are defined as the urgent group (68%) and those with intervention at greater than 24 hours, the elective group (32%). Mean interval from PTCA to operation was 43.5 days; among patients with apparently initially successful PTCA and hospital discharge, mean interval to operation was 138 days. Complete revascularization was carried out in all patients using standard techniques. Although the difference was not statistically significant, patients in the urgent group required intraaortic balloon pump support and inotropic infusions more often and experienced greater postoperative blood loss. Significant increases in the use of lidocaine and blood products were noted in the urgent group. The rates of major complications were 54.4% in the urgent group and 18.8% in the elective group. Mortality was 4.4% in the urgent group and 3.1% in the elective group (not significant); all deaths were cardiac related. There were no late deaths among survivors followed for 3 months to 4 years; 86% were in Functional Class I. We conclude that PTCA is a reasonable approach for some patients with ischemic heart disease. However, mandatory urgent aortocoronary bypass in these patients carries an increased morbidity and mortality, and patients should be selected with care.

A cDNA has been isolated from a human brain expression library using anti-bovine glutamate dehydrogenase (GDH) antibodies. The cDNA has an open reading frame of 774 nucleotides, which codes for 258 amino acids. The 258-amino-acid sequence is 95% homologous to the carboxy terminus of human liver GDH. This high degree of homology indicates that the cDNA codes for brain GDH. Fourteen differences between the amino acid sequence deduced from this cDNA and the sequence reported for human liver GDH suggest that there may be two active human GDH genes. A cRNA probe synthesized from the cDNA detects a 3.7-kilobase (kb) mRNA from human brain. Rat liver and kidney each contain two GDH mRNAs, 3.5 and 2.8 kb, respectively. The 3.5-kb transcript is prominent in rat brain, whereas the 2.8-kb transcript is barely detectable, a result suggesting that GDH gene expression is differentially controlled in rat brain.

The pathway of breakdown of membrane-bound benzodiazepine binding sites has been examined with proteolytic enzymes. Photoaffinity labeled benzodiazepine receptors were degraded for varying amounts of time and at varying enzyme concentrations. The properties of fractions both remaining in the membrane and released into the supernatant were examined for their apparent molecular weight by SDS gel electrophoresis. Trypsin treatment converted the 46K subunits of the GABA/BDZ complex which bind 3H-flunitrazepam into 40K and 27.5K fragments which remained in the membrane and finally a small fragment which was released into the supernatant. An endogenous trypsin-like activity in the membrane fractions has similar proteolytic effects on the membrane bound receptor.

ALTHOUGH neurophysiological, behavioural and biochemical evidence suggests that benzodiazepines (BZ) may affect several neuronal systems within the central nervous system (CNS), recent studies indicate that some of these effects result from a specific interaction with GABAergic transmission1. The precise mechanism of this interaction remains in doubt, as facilitation of GABAergic transmission2, potentiation of GABAergic inhibition3,4, direct activation of γ-aminobutyric acid (GABA) receptors5, and antagonism of GABA-mediated inhibition have all been attributed to the benzodiazepines6,7. In studies from this laboratory8, both the systemic and iontophoretic administration of BZs potentiated an inhibitory response produced by GABA in the dorsal raphe nucleus—suggesting that the potentiation was mediated through a change in the post-synaptic receptor. In addition, direct binding studies using 3H-diazepam have indicated a specific high affinity binding site which may be relevant to the pharmacological actions of BZ in brain9. In this study, we show that GABA can modulate the responsiveness of this BZ binding site since the addition of GABA to cortical membranes in vitro results in an increased affinity of the 3H-diazepam binding site for its ligand. This effect is mimicked by the GABA analogue, muscimol10, and antagonised by the GABA antagonist, (+)bicuculline.

Neurophysiological studies have shown that glycine potentiates the NMDA response in cultured neurons by a strychnine-insensitive mechanism. Autoradiographic data have demonstrated a correspondence between strychnine-insensitive [3H]glycine binding sites and NMDA-sensitive [3H]glutamate binding sites. Here we report that in synaptic plasma membranes from rat brain, the binding of a PCP analog, [3H]TCP, was enhanced more than 5-fold by 1 microM glycine. This glycine stimulation of binding of [3H]TCP was blocked by the competitive NMDA-receptor antagonist, D-AP7. These data provide support for the hypothesis that a unique amino acid recognition site is associated with the proposed NMDA/PCP receptor complex in brain.

An in vivo method for labeling specific benzodiazepine (BDZ) binding sites in brain was developed using intravenously injected [3H]diazepam. Labeling of these sites is blocked by pretreatment of animals with high doses of pharmacologically active BDZs (but not by an inactive BDZ). Using this in vivo binding technique, specific BDZ binding is enhanced by pretreatment of rats with the GABA agonist muscimol or with amino-oxyacetic acid, which increases GABA levels in brain.

The high-affinity binding site for [3H] diazepam has been solubilized from rat brain using 0.5% Lubrol-PX. Using a polyethylene glycol (PEG)-γ-globulin assay, it has been possible to demonstrate solubilization of about 60% of the binding sites in a single step. The solubilized binding site possesses a KD of 11 nM for [3H] diazepam compared to approximately 4 nM for the membrane-bound form, and binding is to a single class of sites. The order of potency of benzodiazepines is identical for the solubilized receptor and the membrane-bound form. Binding of [3H] diazepam is temperature dependent and higher at 4° than 37°C. Both urea and guanidine-HC1 were capable of totally inhibiting binding, and this inhibition was partly reversible; neither sulfhydryl groups nor carbohydrate moieties seem to be important for binding. γ-Aminobutyric acid which enhanced [3H] diazepam binding to membrane fractions was without effect on the solubilized binding site.

We studied the regulation by glucocorticoids of glutamine synthetase in L6 muscle cells in culture. Glutamine synthetase activity was strikingly enhanced by dexamethasone. The dexamethasone-mediated induction of glutamine synthetase activity was blocked by RU38486 [11 beta-(4-dimethylaminophenyl)17 beta-hydroxy-17 alpha-(prop-1-ynyl)estra-4,9-dien-3-one], a glucocorticoid antagonist, indicating the involvement of intracellular glucocorticoid receptors in the induction process. RU38486 alone was without effect. Northern blot analysis revealed that dexamethasone-mediated enhancement of glutamine synthetase activity involves increased levels of glutamine synthetase mRNA. Increased enzyme activity was specific for glucocorticoids; other steroid hormones were essentially without effect. The induction of glutamine synthetase was selective, in that glutaminase activity was not induced by dexamethasone treatment of L6 cells. Thus, glucocorticoids regulate the expression of glutamine synthetase mRNA in cultured muscle cells via interaction with intracellular receptors. Such regulation may be relevant to control of glutamine production by muscle.

Several recent studies in animals and man indicate that corticosteroids may alter catecholaminergic activity in both the peripheral and central nervous systems. We administered 1 mg of the synthetic glucocorticoid, dexamethasone, to 12 drug-free healthy volunteers and measured plasma homovanillic acid (HVA) and 3-methoxy-4-hydroxyphenylglycol (MHPG). Dexamethasone was administered at 11 p.m. and blood was collected at 4 p.m. on the preceding and subsequent days. Dexamethasone administration resulted in a significant increase in plasma HVA but did not consistently affect MHPG. All subjects showed a suppression of serum cortisol to values less than 5 micrograms/dl while prolactin levels were unaltered. In an additional group of nine volunteers, we administered 2 mg of dexamethasone and observed a similar increase in plasma HVA without change in plasma MHPG, indicating a selective effect on dopamine metabolism. Implications of these findings for an understanding of the neurochemical and behavioral changes seen with steroid administration and in explaining previous results on plasma MHPG/HVA ratios in delusional depression are discussed.

To achieve academic success, students must be adept in a variety of kinds of remembering. They must remember in order to recite or to make presentations in class. They must remember in a different way in order to compose coherent and convincing papers. They must remember in yet another way in order to excel in taking tests. Furthermore, variety characterizes not only the purposes of remembering but also the content to be remembered. Students must remember information, in the form of facts, concepts, or principles. In addition, they must remember procedures of the kinds involved in constructing proofs or solving problems.

Advancements on two major fronts in cognitive and developmental psychology provide a foundation for reforming the character of academic instruction. Advancements on one front, sometimes referred to as domain-specific cognition, promise to identify the structures of content knowledge students need in order to become proficient in particular subject-matter domains. Advancements on the second front, sometimes referred to as metacognition, promise to specify the knowledge of their own cognitive procedures students need in order to acquire and deploy these procedures effectively. Even if both of these promises are fulfilled, however, their impact on the outcomes of education may be negligible unless major changes are made in certain features that typify instruction in academic courses.

Glutamic acid decarboxylase (GAD) mRNA was quantified in different regions of rat brain using an antisense RNA probe (ribo-probe) prepared from a cloned feline cDNA. In all brain regions studied a single band of GAD mRNA of approximately 3.7 kb was detected. The level of GAD mRNA was highest in the cerebellum, followed by the hypothalamus greater than thalamus greater than striatum greater than hippocampus greater than frontal cortex = parietal cortex greater than or equal to medulla = pons. Since GAD has been previously localized to intrinsic neurons of the striatum, we examined the effects of intrastriatal kainic acid administration on striatal GAD mRNA. The level of GAD mRNA in the kainic acid-lesioned striatum was reduced by 70-75% when compared to the contralateral (unlesioned) striatum. In contrast, the level of glutamine synthetase (an enzyme localized to glia) mRNA was increased approximately 290% in the kainic acid-lesioned striatum. There were no significant differences in GAD mRNA levels between the ipsilateral and contralateral cerebral cortices and hippocampi of rats injected with intrastriatal kainic acid.

IT HAS been a common clinical practice to "reperitonealize" areas of injury to the visceral peritoneum in order to prevent the formation of adhesions between such areas and omentum, intestine or other intraabdominal structures. The usual method of doing this for serosal injuries to the bowel is to draw adjacent uninjured serosa together over the area of injury with interrupted sutures of a fine nonabsorbable material, such as 0000 silk, taking delicate bites of tissue with a small round-pointed needle. Experiments carried out by Chandy in this laboratory have indicated that silk itself commonly becomes encapsulated by omentum and that the usual seromuscular stitch tied in place would, of itself, produce an adhesion in the experimental animal (rat). EXPERIMENTAL STUDIES The following experiments were carried out to see if the incidence of adhesions resulting from areas of bowel denuded of serosa was reduced or increased by oversewing. The animals used

For the past two years international aid institutions, led by the World Bank, have been putting substantial pressure on African countries to adopt a series of policy measures which they believe will help reverse the decline of per capita food production on the continent. Particularly important in this set of recommended policy prescriptions has been increasing prices on basic food commodities and turning over the marketing of basic food commodities to the private sector. Some African countries have adopted one or both of these policies, either in response to donor pressure or for their own reasons. The paper by Christensen and Witucki examines the initial evidence to see what impact these policies, usually price policy, have on agricultural production. It then examines other policies and the state of agricultural technology to assess the impact on agricultural production that can be expected from various instruments available.

In addition to radiation from naturally occurring radioactive materials and cosmic rays, individuals in developed countries receive radiation doses to bone marrow and gonads from the medical diagnostic use of X rays. A brief discussion of radiation epidemiology shows that deleterious effects are low even when doses are high. The concept of acceptable risk is introduced to help evaluate the small, but still existent, risks of radiation dose. Examples of bone marrow and gonadal doses for representative X-ray examinations are presented along with the current best estimates, per unit of X-ray dose, of the induction of leukemia or of genetic harm. The risk to the patient from an examination can then be compared with the normal risk of mortality from leukemia or of the occurrence of genetic defects. The risk increase is found to be very low. The risks to unborn children from radiographic examinations are also discussed. The benefit to the patient from information obtained from the examination must be balanced against the small risks.