Showing papers by "McMaster University published in 1977"

Characteristics of a Human Cell Line Transformed by DNA from Human Adenovirus Type 5

Abstract: Summary Human embryonic kidney cells have been transformed by exposing cells to sheared fragments of adenovirus type 5 DNA. The transformed cells (designated 293 cells) exhibited many of the characteristics of transformation including the elaboration of a virus-specific tumour antigen. Analysis of the polypeptides synthesized in the 293 cells by labelling with 35S-methionine and SDS PAGE showed a variable pattern of synthesis, different in a number of respects from that seen in other human cells. On labelling the surface of cells by lactoperoxidase catalysed radio-iodination, the absence of a labelled polypeptide analogous to the 250 K (LETS) glycoprotein was noted. Hybridization of labelled cellular RNA with restriction fragments of adenovirus type 5 DNA indicated transcription of a portion of the adenovirus genome at the conventional left hand end.

Gap junctions: their presence and necessity in myometrium during parturition

Abstract: Thin sections of longitudinal and circular muscle of myometrium obtained from rats during pregnancy, at term, during delivery, and postpartum were quantitatively examined in the electron microscope. Gap junctions (low resistance pathways) were only present during or immediately prior to delivery and immediately postpartum. The absence of gap junctions during gestation may be necessary for maintenance of pregnancy, while their occurrence during parturition may lead to effective termination of pregnancy.

A Developmental Perspective

Abstract: A brief outline of what is meant by a developmental perspective is considered prior to examining its application to occupational therapy. Development concepts useful to practitioners are considered. This is followed by a review of the two present theories developed by occupational therapists which are based on developmental models. This information is given as a basis for the main objective of the paper: To propose a develpmental perspective for occupational therapy based on play behaviour.

Carbon-14: Direct Detection at Natural Concentrations

Abstract: The14C atoms naturally present in a piece of 19th-century wood have been detected directly by means of a tandem Van de Graaff accelerator used as a high-energy mass spectrometer. The14C ions were easily resolved from interfering ions with the use of a ΔE-E detector telescope (this telescope consists of a pair of detectors; one of them measures the specific ionization, ΔE, and the sum of the signals from both detectors gives the total energy for each ion, ET). The technique offers a number of practical advantages.

Developmental dyslexia: two right hemispheres and none left

Abstract: Developmental dyslexia may be associated with (i) bi-hemisphere representation of spatial functions, in contrast to the right-hemisphere specialization observed in normal children, and (ii) typical left-hemisphere representation of linguistic functions, as is observed in normal children. The bilateral neural involvement in spatial processing may interfere with the left hemisphere's processing of its own specialized functions and result in deficient linguistic, sequential cognitive processing and in overuse of the spatial, holistic cognitive mode. This pattern of cognitive deficits and biases may lead dyslexics to read predominantly with a spatial-holistic cognitive strategy and neglect the phonetic-sequential strategy. Such an approach in learning to read phonetically coded languages, such as English, many be inefficient and limited.

Afterdischarge thresholds and kindling rates in dorsal and ventral hippocampus and dentate gyrus

Abstract: Electrodes were implanted to dorsal hippocampus (CA1), ventral CA1, DOrsal dentate gyrus or ventral dentate gyrus. Epileptiform afterdischarge (AD) thresholds were lower in dorsal areas than in ventral areas. Dorsal areas, however, required a greater number of stimulations to develop ("kindle") a fully generalized convulsion than did ventral areas. Thresholds and kindling rates in the dentate gyrus were intermediate between dorsal and ventral CA1, except for the ventral dentate which had higher AD thresholds than ventral CA1. Secondary sites within the hippocampus subsequently kindled within a few stimulations following completion of kindling in the primary site, regardless of which hippocampal area served as the primary site.

Prevention of venous thrombosis in patients with intracranial disease by intermittent pneumatic compression of the calf.

Abstract: In a randomized study of 128 patients, we evaluated intermittent pneumatic compression of the calf in the prevention of leg scan-detected venous thrombosis in intracranial disease. Pneumatic compression of the calf for 5 days reduced the rate of venous thrombosis from 12 of 63 control patients (19.1 percent) to one of 65 patients (1.5 percent) given prophylaxis (p = 0.00082). In patients who had craniotomy for brain tumor, subarachnoid hemorrhage, or subdural hematomas, calf compression reduced the incidence of venous thrombosis from nine of 49 control patients (18.4 percent) to one of 53 patients (1.9 percent) given prophylaxis (p = 0.0051). In patients who remained at risk after 5 days, the rate of venous thrombosis was no different in the control group than in the group that had received prophylaxis.

Design of a stripline log-periodic dipole antenna

Abstract: A procedure is given for designing a two-layer stripline log-periodic dipole (LPD) antenna array. Measured input impedance and far-field characteristics are demonstrated for a 12-element array for 1-2 GHz operation that are in good agreement with design specifications.

The Professionalization of Medical Students: Developing Competence And A Cloak of Competence*

Abstract: This paper describes how medical students in an innovative educational setting adopt a cloak of competence as a critical part of the professionalizi~tion process. Faced with inordinate and variable expectations to develop and display competence, students professionalize by distancing themselves from those they interact with and by adopting and manipulating the symbols of their new status. Students were observed to engage in impression management to convince others and themselves that they are competent and confident to facethe immense responsibilities of their privileged role. The data were collected by means of participant observation and interviews. INTRODUCTION. The cultural study of a population which, unlike that of a small homogeneous community, is of diverse origins and experiences encounters many special problems. It is necessary to discover what, in the mass of that experience, is the central and consistent element in the life activities of the population under consideration. Dr. Edgerton has found this commonality in the efforts of these people (mentally retarded released into the community from institutions) to envelop themselves in a 'cloak of competence', in their need to deny themselves the reality of their condition, and in the closely related requisite that they hide-or convince themselves they have hidden-the fact that they have been adjudged deficient (Forward by Walter Goldschmidt in Edgerton, 1967: v-vi). (emphasis ours) The processes of covering up personal incompetence, the appearance of incompetence, or feelings of incompetence, are not restricted to the mentally retarded but are characteristic of participants in occupations and societies that place high value on cognitive skills and abilities. Edgerton observes that institutionalized retardates, released to the community, face the problem of acting "normally" and not revealing their secret. Goffman has suggested that managing and manipulating impressions, and conveying a competence one would like to be believed and accepted, characterizes interactions where participants desire to be successful. Individuals and groups maintain fronts conveying certain impressions and covering up less desirable aspects of personality or behavior (Goffman, 1959). Though managing impressions and role playing are basic parts of the sociological drama, they may be more obvious where participants perceive a potentially critical and condemning audience. This is obvious when the audience has high expectations of competence for others and expect, if not demand, displays of competence, particularly when those assumed to be competent control the situation and act or make decisions affecting the well-being of others. The affected parties then look for cues and indications of personal and/or collective (institutional) competence and practitioners organize a

Learning Real Feelings: A Study of High Steel Ironworkers' Reactions To Fear and Danger

Abstract: This paper describes how the author came to learn, through nine months of participant observation, how high steel ironworkers feel and act towards the dangers of their work Ironworkers define much of their work situation as dangerous, and have developed, out of interactions about this common problem, collectively shared perspectives for enhancing control over the work situation These processes of control include testing and assessing other workers, communicating these evaluations to others, and establishing worker reputations Similar processes of control are applied to bosses, contractors, and others whose actions impinge on worker autonomy and self-interest These processes of control are very analogous to those describing other dangerous occupations The perception of danger by workers in quite different occupations leads them to develop similar mechanisms of control over their work fellows and environment

Effect of magnon-phonon thermal relaxation on heat transport by magnons

Abstract: The experimental evidence for heat transport by magnons in magnetic insulators is reviewed. It is noted that in a thermally isolated system, the magnon temperature comes to equilibrium with the phonon temperature with a finite relaxation time ${\ensuremath{\tau}}_{\mathrm{mp}}$. Since a conventional thermal-conductivity experiment is inherently a nonequilibrium situation, the steady-state magnon temperature gradient will differ from that of the phonons. A calculation is presented to show how the experimentally measured conductivity depends on ${\ensuremath{\tau}}_{\mathrm{mp}}$, as well as on the intrinsic magnon and phonon conductivities ${K}_{m}$ and ${K}_{p}$. In the limit of very long relaxation times, only ${K}_{p}$ is experimentally observed, regardless of the magnitude of ${K}_{m}$. The calculation is illustrated for the ferrimagnet YIG and the antiferromagnet Mn${\mathrm{F}}_{2}$, using magnon-phonon relaxation times measured by magnetic-resonance experiments. It is shown that ${\ensuremath{\tau}}_{\mathrm{mp}}$ for YIG is short enough to allow magnon heat transport to be observed, which is in agreement with experimental results. It is also shown that the long relaxation time for Mn${\mathrm{F}}_{2}$ may be responsible for the absence of magnon conductivity in this material. This general explanation may also apply to many other magnetic systems.

A Comparison of the Bronchodilator Activity of Sch 1000 and Salbutamol

Abstract: The effects of the beta 2-adrenergic agonist, salbutamol, 200 mug, and the cholinergic antagonist, Sch 1000, 40 mug, have been compared in 25 asthmatic patients using a single dose, double-blind, crossover trial design. Salbutamol aerosol produces a greater degree of bronchodilatation than Sch 1000 aerosol during the initial three hours following drug administration. There is no significant difference in the bronchodilator effects of the two drugs in the interval four to eight hours after drug administration. Nonatopic patients showed less difference in bronchodilator response to each of the two drugs than atopic patients. Neither drug showed any significant adverse effect on blood pressure, pulse rate, or electrocardiogram. In six asthmatic patients the effect of the combination of salbutamol, 200 mug, and Sch 1000, 40 mug, was evaluated. The combination produced a longer duration of bronchodilatation than either drug alone when compared to placebo.

Single unit and lesion experiments on the sensory inputs to the hippocampal cognitive map.

Abstract: The hippocampal cognitive map theory states that the hippocampus calculates the animal's location in an environment and also the locations of objects such as rewards and threats In this paper we report single cell experiments which explored how sensory inputs are used by the hippocampus to calculate spatial information and behavioural experiments which tested the sensory capabilities of fornix-lesioned rats Both sets of experiments were done in cue-controlled enclosures which contained only a few distant cues by which the rat could locate itself and the goal Other cues were eliminated by rotating the constellation of cues and the goal from trial to trial The results of the single cell experiment show that the place fields of hippocampal cells recorded in this environment are related to the controlled cues and, further, that some of these place cells maintain their fields after the removal of any two of four controlled cues The lesion studies show that rats with damaged fornices can learn to approach distant cues behind and below the level of the goal but not ones behind and above the goal A second study showed that the addition of redundant distant cues to the enclosure impairs the learning ability of the lesioned, but not the normal, animals

A Numerical Determination of the Efficiency with Which Spherical Aerosol Particles Collide with Spherical Water Drops Due to Inertial Impaction and Phoretic and Electrical Forces

Abstract: A theoretical model to compute the efficiency with which aerosol particles of radius 0.5≤r≤10 μm collide with water drops of radius a=42, 72, 106, 173, 309 and 438 μm falling at terminal velocity in air is presented. Inertial impaction, thermophoresis, diffusiophoresis and electrical effects are considered. The computations were carried out for ambient conditions of 10°C, 900 mb, and 100%, 95% and 75% relative humidity. The drops and particles were assumed to carry electric charges of 0.2 a2 and 0.2 r2 [esu], respectively, and charges of 2.0 a2 and 2.0 r2 [esu], respectively, where a and r are expressed in centimeters. The external electric field strengths were assumed to range between 0≤E0≤3×105 V m−1. The results of our computations show 1) that the efficiency E with which aerosol particles collide with the drops considered is significantly raised by phoretic and electric forces over and above the efficiency resulting from inertial impaction, this effect being the more pronounced the smaller th...

A new method for physical limnology—tritium‐helium‐3 ages—results for Lakes Erie, Huron, and Ontario1

Abstract: A new method in physical limnology based on the radioactive tracer tritium and its stable daughter product, ‘He, is examined. The 3He produced by the in situ decay of tritium can be used to calculate an effective water mass age. These ages can then be used to estimate gas exchange rates, gas renewal epilimnion.

Substantiation of the Priestley and Taylor Parameter α = 1.26 for Potential Evaporation in High Latitudes

Abstract: Summertime latent heat flux values determined by the energy budget approach are compared to equilibrium model estimates for two shallow lakes and two sedge meadow surfaces in northern Canada. Comparison of energy budget values with equilibrium estimates for each surface show that the latent heat flux can be accurately determined by the Priestley and Taylor (1972) model, where α the ratio of actual to equilibrium evaporation equals 1.26. Results suggest that the Priestley and Taylor parameter is generally applicable to saturated surfaces in high latitudes.

A syntactic investigation of verbal autistic, mentally retarded, and normal children.

Abstract: The syndrome of childhood autism is typified by major abnormalities in language development, yet there are few systematic descriptions of autistic children 's linguistic systems. We have, therefore, begun a comprehensive investigation of the language of verbal autistic children and concentrate in this paper on comparing the syntax used by 10 verbal autistic children matched for nonlinguistic mental age with a group of mentally retarded subjects and normal controls. Two different means of assessing syntactic development were utilized: Lee's Developmental Sentence analysis and Chomsky's Transformational analysis. The autistic group was found to rank significantly lower than either the mentally retarded or the normal group in terms of Developmental Sentence Scores. When a transformational grammar was used to describe the language samples of our subjects the autistic children were typified by a higher error rate and lower level of complexity compared to the other two groups. However, the results also indicate that the grammatical system of autistic children is rule-governed and probably not unlike that of young normal or retarded children. In conclusion, it appears that the syntactic abnormalities characteristic of autism are attributable to an extreme delay in language development as well as to an impaired ability to make use of linguistic rules.

Hydrophobic polymer surfaces and their interactions with blood

Abstract: For the purposes of this review the designation “hydrophobic” is taken to mean solid surfaces on which water and aqueous fluids will not spontaneously spread but will form separated drops having a nonzero contact angle. In a word, they are “nonwettable.” This definition serves to set such surfaces apart from their antithetic category the hydrophilic surfaces, the latter being distinguished by the fact that water will spread on and be absorbed into the bulk of the material. Such materials are the subject of other presentations and will not be discussed further, except for comparative purposes, in this paper. Hydrophobic surfaces are to be taken also as essentially smooth, or at least as having a topography that is not of any specific form. This stipulation again separates them from another major category of materials that have been used in bloodcontact situations. These latter are surfaces that have been purposely designed with a roughened topography to promote development of a thin fibrin layer or other pseudoendothelium when placed in flowing blood. The material of such surfaces is frequently hydrophobic in nature, e.g. Dacron@ and Teflon@, and although they may have microscopic behavior identical to that to be discussed in this paper, they again behave grossly in a different fashion and are dealt with in detail elsewhere in this volume. The purpose of this paper is to review the current status of hydrophobic surfaces as blood-interfacing materials and to discuss the nature of their interactions with various key components of blood. Early recognition of the potential benefit of hydrophobicity in minimizing blood response was provided by the observation of Lister in 1863 that blood coagulation was slower in a rubber container than in glass. Similarly, it was reported by Bordet and Gengou that paraffin-coated surfaces retarded plasma coagulation relative to glass. In more recent times, hydrophobicity has been exploited in the practice of siliconizing glassware in the coagulation laboratory. These observations serve to emphasize that it was blood coagulation that was seen by early workers as the effect to be avoided, and hydrophobic surfaces seem principally to have been proposed in this context. When the search for a blood-compatible surface was intensified in the early 1960s it was widely believed that if coagulation could be avoided, nonthrombogenic surfaces would be achieved. Such thinking may account in part for the use of nonwettable or hydrophobic materials in blood-contact devices. For example, silicones are used in the construction of prosthetic heart valves and the arteriovenous shunts used by

Ammonium and Amino Acids as Regulators of Nitrate Reductase in Corn Roots

Abstract: When amino acids or ammonia are added to plant systems, the effects on the development of nitrate-dependent nitrate reductase activity are variable. In addition, amino acids added singly or as casein hydrolysate may not support a normal growth. A physiologically correct mixture of amino acids, one similar in composition to amino acids released by the endosperm, has been shown to support normal growth and protein synthesis in corn (Zea mays) embryos. In this investigation, we have used the mixture of corn amino acids to determine whether amino acids have an effect on the appearance or disappearance of nitrate reductase activity. The results show that these amino acids partially inhibit the induction of nitrate reductase in corn roots. The effect is more pronounced in mature root than in root tip sections. When glutamine and asparagine are included along with the “corn amino acid mixture,” the inhibition is more severe. Amino acids or amino acid analogues added singly to the induction medium have a similar effect: i.e. when the induction of nitrate reductase is inhibited in the root tips (lysine, canavanine, azaserine, azetidine-2-carboxylic acid, dl-4-azaleucine, asparagine, and glutamine), that inhibition is more severe in mature root sections. Arginine enhanced the recovery of nitrate reductase in root tips but inhibited it in mature root sections. The effect of the amino acids is apparently on some phase of the induction processes (i.e. the uptake or distribution of nitrate or a direct effect on the synthesis of the enzyme) and not on the turnover of the enzyme.