Showing papers by "University of California, Irvine published in 1984"

The Biochemistry of Memory: A New and Specific Hypothesis.

Abstract: Recent studies have uncovered a synaptic process with properties required for an intermediate step in memory storage. Calcium rapidly and irreversibly increases the number of receptors for glutamate (a probable neurotransmitter) in forebrain synaptic membranes by activating a proteinase (calpain) that degrades fodrin, a spectrin-like protein. This process provides a means through which physiological activity could produce long-lasting changes in synaptic chemistry and ultrastructure. Since the process is only poorly represented in the brain stem, it is hypothesized to be responsible for those forms of memory localized in the telencephalon.

Voltage-gated K + channels in human T lymphocytes: a role in mitogenesis?

Abstract: Membrane receptors and ion transport mechanisms probably have an important role in lymphocyte activation leading to T-lymphocyte proliferation in the immune response. Here we have applied a gigaohm-seal patch clamp technique1 to reveal the identity and properties of ion channels in human T lymphocytes. A voltage-dependent potassium channel bearing a resemblance to the delayed rectifier of nerve and muscle cells was found to be the predominant ion channel in these cells. In the whole cell recording conformation, the channels open with sigmoid kinetics during depolarizing voltage steps, reaching a maximum K+ conductance of 3–5 nS. The current subsequently becomes almost completely inactivated during a long-lasting depolarization. Currents through single K+ channels recorded in whole cell and outside-out patch recording conformations reveal a unitary channel conductance of about 16 pS in normal Ringer solution. Thus, the peak current corresponds to approximately 200–300 conducting K+ channels per cell. Phytohaemag-glutinin (PHA), at concentrations that produce mitogenesis, alters K+ channel gating within 1 min of addition to the bathing solution, causing channels to open more rapidly and at more negative membrane potentials. 3H-thymidine incorporation by T lymphocytes following PHA stimulation is inhibited by the ‘classical’ K+ channel blockers tetraethylammonium and 4-aminopyridine, and also by quinine, at doses found to block the K+ channel in voltage-clamped T lymphocytes, suggesting that K+ channels may play a part in mitogenesis.

The Draco Approach to Constructing Software from Reusable Components

Abstract: This paper discusses an approach called Draco to the construction of software systems from reusable software parts. In particular we are concerned with the reuse of analysis and design information in addition to programming language code. The goal of the work on Draco has been to increase the productivity of software specialists in the construction of similar systems. The particular approach we have taken is to organize reusable software components by problem area or domain. Statements of programs in these specialized domains are then optimized by source-to-source program transformations and refined into other domains. The problems of maintaining the representational consistency of the developing program and producing efficient practical programs are discussed. Some examples from a prototype system are also given.

Anteroposterior gradients in cerebral glucose use in schizophrenia and affective disorders.

Abstract: • Local cerebral uptake of deoxyglucose labeled with fluorine 18 was measured by positron emission tomography in 16 patients with schizophrenia and 11 patients with affective disorder. Patients received no medication a minimum of 14 days and an average of 39.8 days. The subjects were administered the deoxyglucose 18F just before receiving a 34-minute 1/s series of unpleasant electrical stimuli to the right forearm while resting with eyes closed in a darkened, acoustically attenuated psychophysiologic testing chamber. Following monitored stimulation in the controlled environment, subjects were scanned and images converted to values of glucose use in micromoles per 100 g per minute according to Sokoloff's model. Data were analyzed with a four-way analysis of variance (ANOVA) with independent groups (normals, schizophrenics, and affectives) and repeated measures for slice level (supraventricular, midventricular, and infraventricular), hemisphere (right, left), and anteroposterior position (four sectors). Both normal subjects and patients showed a significant anteroposterior gradient in glucose use with highest values in the frontmost sector. Patients both with schizophrenia and with affective illness showed less of an anteroposterior gradient especially at superior levels, which was statistically confirmed by ANOVA. Absolute glucose levels in patients, which were actually higher in posterior regions rather than lower in frontal regions, were the largest contributors to the effect. Neither group differences in whole brain glucose use nor left-right asymmetries reached statistical significance. These results are consistent with our earlier reports of a relative hypofrontal function in schizophrenia compared with controls. This report extends this finding to affective illness, sharing a lack of diagnostic specificity with many biologic measures.

Inhibition of human estrogen synthetase (aromatase) by flavones

Abstract: Several naturally occurring and synthetic flavones were found to inhibit the aromatization of androstenedione and testosterone to estrogens catalyzed by human placental and ovarian microsomes. These flavones include (in order of decreasing potency) 7,8-benzoflavone, chrysin, apigenin, flavone, flavanone, and quercetin; 5,6-benzoflavone was not inhibitory. 7,8-Benzoflavone and chrysin were potent competitive inhibitors and induced spectral changes in the aromatase cytochrome P-450 indicative of substrate displacement. Flavones may thus compete with steroids in their interaction with certain monooxygenases and thereby alter steroid hormone metabolism.

Midcarpal instability caused by malunited fractures of the distal radius

Abstract: Thirteen patients with malunited fractures of the distal radius developed symptoms of pain and instability of the midcarpal joint In six cases, a recurrent voluntary midcarpal subluxation was also present during ulnar deviation These symptoms were first noticed several weeks, and at times several months, after all immobilization for the treatment of the original fracture had been discontinued We believe that the loss of the normal palmar tilt of the distal articular surface of the radius prepositions the carpus in a dorsal collapse alignment, which enables this instability to develop Although the instability is localized to the midcarpus, it is treated best, in our opinion, by a corrective osteotomy of the distal radius In nine patients, osteotomies resulted in relief of preoperative symptoms and correction of midcarpal instability In one patient, osteotomy of the radius was deemed unnecessary because the loss of palmar tilt of the radius was minimal Instead the midcarpal (triquetrohamate) joint was stabilized by ligament reconstruction Only transient correction was obtained, with later recurrence of the voluntary midcarpal subluxation

The control of information systems developments after implementation

Abstract: Cet article etudie un des aspects des dernieres etapes dans le cycle de vie d'un systeme d'information a base d'ordinateur (CBIS's). On examine 4 metaphores de l'implementation d'un CBIS qui traitent des differentes esperances sur les developpements de calcul et les resultats probables: l'evolution technologique, la rationalite economique, le mouvement de structure et la politique d'organisation

Inhibitors of lysosomal enzymes: accumulation of lipofuscin-like dense bodies in the brain

Abstract: Injections of leupeptin (a thiol proteinase inhibitor) or chloroquine (a general lysosomal enzyme inhibitor) into the brains of young rats induced the formation of lysosome-associated granular aggregates (dense bodies) which closely resembled the ceroid-lipofuscin that accumulates in certain disease states and during aging The dense material increased in a dose- and time-dependent fashion and was differentially distributed across brain regions and cell types These observations provide clues to the origins of ceroid-lipofuscin and suggest means for studying the consequences of its accumulation

Evolution and organizational information systems: an assessment of Nolan's stage model

Abstract: Richard Nolan's stage model is the best known and most widely cited model of computing evolution in organizations. The model's development over a decade demonstrates its own evolution from a simple theory, based on the factoring of change states indicated by changes in computing budgets, to an elaborate account of the characteristics of six stages of computing growth. An analysis of the model's logical and empirical structure reveals a number of problems in its formulation that help to account for the fact that its principal tenets have not been independently validated. The model is shown to be an “evolutionistic” theory within the theories of evolution in the social sciences, focusing on assumed directions of growth and an implied end state toward which growth proceeds, and suffering from problems inherent in such theories. Further research based on an “evolutionary” view of computing growth is suggested as a means of improving theories of computing in organizations.

An Essay on Software Reuse

Abstract: This paper explores software reuse. It discusses briefly some economic incentives for developing effective software reuse technology and notes that different kinds of software reuse, such as direct use without modification and reuse of abstract software modules after refinement, have different technological implications. It sketches some problem areas to be addressed if we are to achieve the goal of devising practical software reuse systems. These include information retrieval problems and finding effective methods to aid us in understanding how programs work. There is a philosophical epilogue which stresses the importance of having realistic expectations about the benefits of software reuse.

Cell biology of synaptic plasticity.

Abstract: The nervous system of mammals retains throughout the animals' life-span the ability to modify the number, nature, and level of activity of its synapses. Synaptic plasticity is most evident after injury to the nervous system, and the cellular and molecular mechanisms that make it possible are beginning to be understood. Transplantation of brain tissue provides a powerful approach for studying mechanisms of synaptic plasticity. In turn, understanding the response of the central nervous system to injury can be used to optimize transplant survival and integration with the host brain.

Mercury(II)‐ and Palladium(II)‐Catalyzed [3,3]‐Sigmatropic Rearrangements [New Synthetic Methods (46)]

Abstract: Mercury(II) and palladium(II) salts have found broad applications as catalysts for [3,3]-sigmatropic rearrangements leading to formation of CO, CN, CS, and CC σ bonds. Increases in reaction rate are often very large (1010 – 1014 at 1 M catalyst concentration) and allow many previously difficult transformations to be conducted at or near room temperature, often with attendant increases in stereoselectivity and decreases in by-product formation. The mechanism of these catalyzed transformations is briefly discussed, and evidence is summarized to suggest that many follow a cyclization-induced rearrangement mechanism.

Optimizing group judgmental accuracy in the presence of interdependencies

Abstract: Consider a group of people confronted with a dichotomous choice (for example, a yes or no decision). Assume that we can characterize each person by a probability, pi, of making the 'better' of the two choices open to the group, such that we define 'better' in terms of some linear ordering of the alternatives. If individual choices are independent, and if the a priori likelihood that either of the two choices is correct is one half, we show that the group decision procedure that maximizes the likelihood that the group will make the better of the two choices open to it is a weighted voting rule that assigns weights, wi, such that

Determinants of web spider species diversity: Vegetation structural diversity vs. prey availability

Abstract: The hypotheses that vegetation structural diversity and prey availability determine alpha diversity were examined for scrub- and meadow-inhabiting web spider species assemblages along elevational gradients in Costa Rica and California Prey availabilities were estimated by sticky trap catches, using only the orders and size classes of insects actually captured by the spiders The measured component of vegetation structural diversity was the maximum tip height in 20 cm increments from 0 to 20 m Spider species diversity and vegetation tip height diversity were both expressed by the Inverse Simpson Index Web spider species diversity is highly significantly correlated with vegetation tip height diversity Prey availability is not a significant predictor of web spider species diversity in these habitats

Enhanced neural response to familiar olfactory cues

Abstract: Norway rat pups have an enhanced olfactory bulb response to a familiar odor. A specific complex of glomeruli showed increased carbon-14-labeled 2-deoxy-D-glucose uptake in response to peppermint odor in 19-day-old pups exposed to peppermint on days 1 to 18 after birth, relative to control pups that had been exposed to clean air. The increased activity was not due to increased respiration of the familiar odor.

Non-function of a Moloney murine leukaemia virus regulatory sequence in F9 embryonal carcinoma cells

Abstract: Moloney murine leukaemia virus (M-MuLV) infection of embryonal carcinoma (EC) cells results in the integration of proviral DNA into the host cell genome, but not in virus production. One suggested explanation for the lack of viral gene expression in EC cells has been methylation of the integrated viral DNA. However, subsequent reports indicated that integration of the M-MuLV DNA occurs soon after infection, but that viral DNA methylation occurs considerably later. Nevertheless, viral gene expression is not observed even at early times. One possible explanation is that certain M-MuLV regulatory sequences do not function in EC cells. We now present evidence which supports this hypothesis.

Adult testosterone levels influence the morphology of a sexually dimorphic area in the mongolian gerbil brain

Abstract: This research shows that the medial preoptic area-anterior hypothalamus (MPOA-AH) of the gerbil contains a sexually dimorphic area (SDA) whose morphology is influenced by adult gonadal steroids. The characteristics of the SDA were studied initially in gonadally intact males and females and later in males and females that had been gonadectomized or gonadectomized and given testosterone. Coronal sections through the MPOA-AH were stained with thionin to visualize the SDA. In male gerbils, the SDA is a darkly staining, hook-shaped structure on either side of the third ventricle, above the suprachiasmatic nuclei and below the anterior commissure. Within the male SDA lies a small, dense cluster of cells, the SDA pars compacta (SDApc). In female gerbils, the SDA is more ovoid and diffuse and the SDApc is absent. Camera lucida tracings and planimeter measurements of the SDA showed that the total volume of the SDA is similar in the two sexes, but the proportion of the SDA that stains darkly and/or stands out clearly from the surround (dark volume) is larger in males. Gonadectomy decreases both total and dark volume of the SDA in both sexes and decreases the volume of the SDApc in males. Testosterone treatment prevents these changes. This is the first report of changes in the gross morphology of the mammalian brain after steroid hormone manipulations in adulthood. The changes in the SDA may be related to testosterone activation of scent marking behavior.

The effects of death qualification on jurors' predisposition to convict and on the quality of deliberation

Abstract: This study provides a straightforward test of the proposition that people who are permitted to serve on juries in capital cases (death-qualified jurors) are more likely to convict a defendant than are people who are excluded from serving on capital juries due to their unwillingness to impose the death penalty (excludable jurors). A sample of 288 subjects classified as death-qualified or excludable under theWitherspoon standard watched a 2 1/2-hour videotape of a simulated homicide trial including the judge's instructions, and gave an initial verdict. Death-qualified subjects were significantly more likely than excludable subjects to vote guilty, both on the initial ballot and after an hour's deliberation in 12-person juries. Nine juries were composed entirely of death-qualified subjects (death-qualified juries), while 10 contained from 2 to 4 excludable subjects (mixed juries). On postdeliberation measures, with initial death-penalty attitudes controlled, subjects who had served on the mixed juries were generally more critical of the witnesses, less satisfied with their juries, and better able to remember the evidence than subjects from the death-qualified juries, suggesting that diversity may improve the vigor, thoroughness, and accuracy of the jury's deliberations.