Showing papers by "Boston University published in 1975"

Olivocochlear and vestibular efferent neurons of the feline brain stem: their location, morphology and number determined by retrograde axonal transport and acetylcholinesterase histochemistry.

Abstract: Anterograde degeneration studies have shown that the cochlear and vestibular receptor organs receive an efferent innervation from neurons in the brain stem. This pathway may provide a mechanism by which the CNS could modulate its own afferent input. The neurons which provide this innervation have so far escaped positive identification with methods which depend on retrograde cell changes after axotomy. In the present study, horseradish peroxidase (HRP) was injected into the labryinths of kittens and after allowing 24 hours for the retrograde axonal transport of this tracer, its presence in neurons of the brain stem was demonstrated histochemically. Because there is evidence that the efferent innervation of the labyrinth is cholinergic, acetylcholinesterase (AChE) was also demonstrated histochemically in the same or in adjacent tissue sections. Neurons labelled with HRP were found bilaterally in most periolivary cell groups of the superior olivary complex (cochlear efferents) and in the parvocellular reticular nucleus lateral to the abducens nucleus (vestibular efferents). Counts of labelled neurons yielded estimated totals of 1,700-1,800 cochlear and 400-500 vestibular efferent neurons. Approximately 60% of the neurons in each total were located on the side ipsilateral to the injection. The distribution of HRP-labelled neurons was virtually identical to that of AChE-positive neurons found in adjacent sections, and in those regions with predominantly ipsilateral or contralateral projections, there was an approximate correspondence in number of HRP- and AChE-positive neurons. In tissue sections processed successively for demonstration of HRP and AChE, virtually all HRP-labelled neurons were found to be AChE-positive. These findings suggest that a number of current conceptions regarding labyrinthine efferent systems may need revision.

A Neural Model of Attention, Reinforcement and Discrimination Learning

Abstract: This article discusses several important phenomena wherein present behavior depends on how temporal and geometrical relationships among past events are influenced by competitive feedback.

Eosinophils as mediators of antibody-dependent damage to schistosomula.

Abstract: WE have reported previously1 that damage to schistosomula can be assayed by measuring release of 51Cr from labelled larvae. Using this technique, we have shown that schistosomula can be damaged by a combination of normal human peripheral blood leukocytes and of heat-inactivated sera from patients infected with Schistosoma mansoni1. We now present evidence that the eosinophil is substantially the most active mediator of damage in normal peripheral blood, but that cells from eosinophilic patients are relatively inactive.

Boring Microorganisms and Microborings in Carbonate Substrates

Abstract: Boring or endolithic microorgani sms discussed herein are photosynthetic cyanophytes, eucary—otic green and red algae, and heterotrophic fungi that actively penetrate carbonate substrates. Although their existence has been known since the mid-nineteenth century, new techniques for preparation and study developed within the last decade have brought about significant progress in our understanding of them. Boring microorganisms have been studied in a variety of carbonate substrates, including the shells and skeletons of living organisms or their fragmented remains, and within coastal limestones.

Shape Resonances in K -Shell Photoionization of Diatomic Molecules

Abstract: We show that $K$-shell photoionization spectra of diatomic molecules can exhibit strong shape resonances near threshold. The molecular field is decisive in this phenomenon. It induces the resonant contraction of high-$l$ components of the ionization channels, and it couples these components with low-$l$ components produced in the atomic cores by $K$-shell photoionization. We demonstrate the effect for ${\mathrm{N}}_{2}$ by using the multiple-scattering model. Clear evidence for this phenomenon exists for ${\mathrm{N}}_{2}$, CO, and NO.

Steady and Oscillatory Subsonic and Supersonic Aerodynamics around Complex Configurations

Abstract: A general formulation for steady and oscillatory, subsonic and supersonic, potential linearized aerodynamic flows around complex configurations is presented. A linear integral equation relating the unknown potential on the surface of the body to the known downwash is used. The formulation is applied to the analysis of flowfields around wings and wing-body combinations. The surface is divided into small quadrilateral elements which are approximated with hyperboloidal surfaces. The potential is assumed to be constant within each element. This yields a set of linear algebraic equations. The coefficients are evaluated analytically. Numerical results for steady and oscillatory, subsonic and supersonic flows indicate that the method, is not only more general and flexible than other available methods, but is also fast, accurate, and in excellent agreement with existing results.

Treatment of septic arthritis

Abstract: Surgery and needle aspiraton have been evaluated as initial modes of drainage in 59 patients with acute septic arthritis. Full recovery was noted in 42% treated surgically at the outset. On the other hand, 67% of those treated by needle aspiration recovered without sequelae, despite the greater prevalence in this group of adverse host factor-eg, serious underlying illness, concommitant extraarticular infection, prior arthritis in the infected joint, and recent antibiotic or immunosuppressive therapy.

Loss of Dendritic Spines in Aging Cerebral Cortex

Abstract: Previous work has shown that the dendritic spines of pyramidal neurons of the cerebral cortex are sensitive to a wide variety of environmental and surgical manipulations. The present study shows that the normal aging process also affects these spines. The spines were studied with the light microscope in Golgi preparations from rats ranging in age from 3 to 29.5 months. Visible spines were counted on either 25 or 50 μ segments of the basal dendrites, apical dendrites, oblique branches, and terminal tufts of layer V pyramidal cells in area 17. A progressive loss of spines occurred at each of these loci. The smallest observed spine loss (24%) occurred on the dendrites of the terminal tuft, and the largest (40%) on the oblique branches. Age-related spine loss appears to affect all animals, and for animals of any one age the overall loss is similar. However, the cell-to-cell variability within an individual animal is pronounced, some cells with high spine densities being present at every age examined. As a general rule, there is a positive relationship between visible spine density along the apical dendrite as it traverses layer IV and the thickness of the dendrite. With advancing age, the relatively thick dendrites decrease in number so that the thinner dendrites make up an increasingly larger proportion of the total apical dendrite population. Questions that remain for the future include the genesis of the spine loss, its relation to other aging changes, and its functional significance for the neuron.

Thermal transitions in human plasma low density lipoproteins.

Abstract: Thermal analysis of human plasma low density lipoproteins reveals a broad reversible transition encompassing body temperature. The calorimetric and x-ray scattering data identify this transition as a cooperation, liquid-crystalline to liquid phase change involving the cholesterol esters in the lipoprotein. This behavior requires the presence of a region rich in cholesterol ester within the lipoprotein.

Infant and Caretaking Environment Investigation and Conceptualization of Adaptive Behavior in a System of Increasing Complexity

Abstract: The assignment of bringing together one’s “research perspective, research philosophy, methods, and findings” in one autobiographical account presents some rather obvious and many more subtle difficulties. It is obvious that such a contribution cannot be in the usual format of a scientific paper. And it is difficult to generate a personal synthesis and at the same time to offer it as a research contribution. It has seemed feasible for me only to try to organize and communicate in some reasonably concrete way the course that my work and thought have taken over the last score of years. During that score of years my career in clinical child psychiatry has become largely a commitment to certain problems of early developmental research, in particular, a concern with the question of organization itself in personality development.

The pathology of elastase-induced panacinar emphysema in hamsters.

Abstract: A single dose of crystalline, porcine pancreatic elastase injected intratracheally into hamsters induces widespread alveolar enlargement with subpleural bullae. A uniformly severe lesion is consistently induced by 0-2 mg elastase per 100 g body weight and with negligible mortality. Compared with controls, which showed no lesion, elastase-damaged lungs show a highly significant (P less than or equal to 0-001) increase in alveolar size and a decrease in internal surface area. Taken with the associated physiological abnormalities, these findings closely simulate human emphysema of the panlobular (panacinar) type. Histologically it appears that elastase converts the fine elastic fibres in alveolar walls and pleura into thickened, nodular fibres which may also be broken along their length. With higher doses of elastase, i.e., 0-5 mg/100 g body weight, many pulmonary arteries showed segmental loss of inner and outer elastic laminae, usually with thrombosis on the overlying endothelium. The mechanism of this thrombosis is unclear. These experiments suggest that damage to elastic fibres may be an important element in the development of human panacinar emphysema, and that the damage could be one pathogenetic mechanism which produces damage of elastic fibres.

A hospital stress rating scale.

Abstract: When 261 medical and surgical patients at a community hospital were asked to rank order 49 events related to the experience of hospitalization from most to least stressful, results indicated the subjects were capable and willing to order the events. Moreover, they showed a high degree of consensus as to how the events should be ordered. The rank order of these events provides a tool that can be used to quantify the measurement of psychosocial stress experienced by hospital patients.

Some Analyses of Amnesic Syndromes in Brain-Damaged Patients

Abstract: The contribution of the hippocampus to the normal operation of human memory processes has been quite clearly delineated by Milner and her collaborators during the past 15 years. These investigators have documented the nature of the memory disorder following injury to the hippocampus and, in addition, have provided support for the dual process theory of memory. Since these investigations are quite well known, only a brief summary of their major findings will be presented here prior to a more thorough discussion of two closely related issues: (1) an analysis of the amnesic disorders of alcoholic Korsakoff patients and (2) an examination of the amnesic syndromes produced by different forms of brain damage. The alcoholic Korsakoff patient is clinically similar to patients with bilateral hippocampal damage but, unlike these patients, he has suffered extensive midline limbic-diencephalic damage involving the nucleus medialis dorsalis and/or mammillary bodies (Victor et al., 1971). Since both of these structures have major anatomical connections with the hippocampus as well as other limbic entities, a thorough behavioral investigation of the amnesia of Korsakoff patients may enrich our understanding of the manner in which various limbic and diencephalic structures interact in the processing of information.

Science in Flux

Abstract: To what extent and in what respect is science intellectually valuable? This is a controversial matter. What is hardly disputed is that what is alterable in science is of mere ephemeral value; and what is valuable in it is that which is more universal and permanent, that which is more solid and lasting. One of the very few philosophers who oppose this accepted view is Sir Karl Popper. In his view, science is so valuable because of its open- mindedness, because any of its achievements may at any time be given up and newer achievements may be hoped for to replace the relinquished ones. Science, says Popper, is at constant war with itself, and it progresses by revolutions and internal conflicts.