Showing papers by "McGill University published in 1974"

Origin, differentiation and renewal of the four main epithelial cell types in the mouse small intestine. V. Unitarian Theory of the origin of the four epithelial cell types.

Abstract: The previous articles of this series provided presumptive evidence that the four main differentiated cell types in the epithelium of the mouse small intestine: villus columnar, mucous, entero-endocrine, and Paneth cells, originate from the same precursor, the crypt-base columnar cell. In the present work, direct evidence was obtained in support of this view. It was first found that crypt-base columnar cells phagocytose non-viable cells in their vicinity, with the result that a large phagosome appears in the cytoplasm. Such phagosomes were then used as markers to follow the evolution of crypt-base columnar cells. In normal control animals, a rare crypt-base columnar cell includes a large phagosome containing Paneth cell remnants. By six hours after injection of two μCi 3H-thymidine per g body weight, a fair number of crypt-base columnar cells include a different type of phagosome containing labeled nucleus and granulefree cytoplasm, which is attributed to phagocytosis of a labeled crypt-base columnar cell killed by beta-radiation from the incorporated 3H-thymidine. By 12 hours after 3H-thymidine injection, phagosomes have appeared in partly differentiated mid-crypt columnar cells and oligomucous cells; by 18–24 hours, in fully differentiated columnar cells and in Paneth cells; and by 30 hours, in an entero-endocrine cell. Since phagosomes are first found in crypt-base columnar cells and only later in the four differentiated cell types, it is concluded that crypt-base columnar cells transform into cells of these four types and, therefore, behave as the stem cells of the epithelium. The finding of rare epithelial cells containing two different types of secretory material (either mucous globules and entero-endocrine granules, or mucous globules and Paneth cell granules) confirms that the stem cells are multipotential. These findings support the Unitarian Theory of epithelial cell formation in the small intestine.

The Rise and Future Demise of the World Capitalist System: Concepts for Comparative Analysis

Abstract: The growth within the capitalist world-economy of the industrial sector of production, the so-called industrial revolution, was accompanied by a very strong current of thought which defined this change as both a process of organic development and of progress. There were those who considered these economic developments and the concomitant changes in social organization to be some penultimate stage of world development whose final working out was but a matter of time. These included such diverse thinkers as Saint-Simon, Comte, Hegel, Weber, Durkheim. And then there were the critics, most notably Marx, who argued, if you will, that the nineteenth-century present was only an antepenultimate stage of development, that the capitalist world was to know a cataclysmic political revolution which would then lead in the fullness of time to a final societal form, in this case the classless society.

Origin, differentiation and renewal of the four main epithelial cell types in the mouse small intestine. II. Mucous cells

Abstract: The mucous cell population of duodenum, jejunum and ileum was investigated in the light and electron microscopes with the help of radioautography in mice sacrificed at various times after single injection or continuous infusion of 3H-thymidine. Mucous cells are characterized by globules of mucus and by dilated cisternae of rough endoplasmic reticulum. Two subgroups of mucous cells, one called common and the other granular, may be identified. The granular mucous cells differ from the common ones by the presence of small dense granules embedded within the mucous globules. Each subgroup is further divided into immature oligomucous cells containing few mucous globules, and mature goblet cells with a large accumulation of mucous globules. Common and granular oligomucous cells are found exclusively in the crypt, mainly within the lower mid-crypt, whereas the corresponding two types of goblet cells are present in the upper part of the crypts and in the lower part of the villi. Only common mucous cells are observed in the upper part of the villi. The two types of oligomucous cells, but not goblet cells, have the ability to take up 3H-thymidine and divide. Electron microscopic radioautography demonstrates that, as oligomucous cells migrate upwards, they transform into goblet cells. The latter then migrate to the villus epithelium. In the case of granular mucous cells, this migration is associated with a gradual loss of the characteristic dense granules, so that the granular goblet cells reaching the upper part of the villi become common goblet cells. The goblet cells in the villus epithelium, regardless of their origin, ascend towards the villus tips where they are lost through the extrusion zones. The turnover time of common mucous cells is about three days, as for columnar cells; and that of granular mucous cells, somewhat shorter. In both cases, the divisions of oligomucous cells account only for the production of about half the mucous cells present. Hence, the other half must be derived from precursors other than oligomucous cells. Since a few crypt-base columnar cells contain the odd mucous globule, they are suspected of being the precursors of the two types of oligomucous cells and, through them, of the entire mucous cell population.

Equalities and Inequalities for Ranks of Matrices

Abstract: (1974). Equalities and Inequalities for Ranks of Matrices. Linear and Multilinear Algebra: Vol. 2, No. 3, pp. 269-292.

Studies of insulin, growth hormone and prolactin binding: tissue distribution, species variation and characterization.

Abstract: The specific binding of 125I-labeled insulin, hGH and oPRL was surveyed in crude membrane preparations of various tissues of the monkey, rat, guinea pig, rabbit, sheep, pigeon, and frog. Binding varied greatly with the species examined. The highest binding of 125I-insulin was seen in guinea pig tissues, especially kidney, fetal placenta and liver. Significant binding of 125I-insulin was seen in many but not all known target tissues, and in other tissues as well (viz. placental, adrenal, brain). The binding of 125I-hGH and 125I-oPRL paralleled each other, except in rabbit liver, and was highest in rabbit liver and adrenal, female rat liver, frog kidney, and several sheep tissues. There was no relation between phylogenetic proximity to man and the level of specific binding of 125I-hGH observed. The lowest binding of 125I-hGH was in male rat liver and various tissues of the mpnkey and guinea pig, a high proportion of which showed significant binding of 125I-insulin. 125I-insulin was displaced from the membra...

Thermoset characterization for moldability analysis

Abstract: The injection molding of thermosetting compounds involves complex interactions between material parameters and molding conditions, on one hand, and moldability and the ultimate properties of molded parts, on the other hand. The main role of the molding variables may be related to their effects on the cure time and temperature and on the flow and thermal phenomena that affect orientation and residual stresses. These effects are manifested in the ultimate mechanical properties and shrinkage of the molded articles. Only scattered empirical data are available on the effects of material parameters, like the basic kinetic, thermal, rheological, and pressure-volume-temperature properties of thermosetting compounds. The lack of useful information in this area may be related to the unavailability of sufficient, satisfactory data on the above properties. This situation has also resulted in limitations on meaningful work towards the mathematical modelling of the molding process, which would be useful for the optimization of production rates and product quality. The paper summarizes the status of work in this area with emphasis on recent results relating to kinetic, thermal, and rheological characterization of thermosetting molding compounds.

Comparative Robustness of Six Tests in Multivariate Analysis of Variance

Abstract: Monte Carlo methods were used to study the performance of the largest-root test, two trace-type tests and three determinantal tests in the fixed-effects MANOVA model when certain assumptions are violated. Results indicated that for protection against nonnormality and heterogeneity of covariance matrices, the largest-root test should be avoided, while the Pillai-Bartlett trace test may be recommended as the most robust of the MANOVA tests, with adequate power to detect true differences in a variety of situations.

Synthesis, migration, and release of precursor collagen by odontoblasts as visualized by radioautography after [3h]proline administration

Abstract: The elaboration of dentin collagen precursors by the odontoblasts in the incisor teeth of 30-40-g rats was investigated by electron microscopy, histochemistry, and radioautography after intravenous injection of tritium-labeled proline. At 2 min after injection, when the labeling of blood proline was high, radioactivity was restricted to the rough endoplasmic reticulum, indicating that it is the site of synthesis of the polypeptide precursors of collagen, the pro-alpha chains. At 10 min, when the labeling of blood proline had already declined, radioactivity was observed in spherical portions of Golgi saccules containing entangled threads, and, at 20 min, radioactivity appeared in cylindrical portions containing aggregates of parallel threads. The parallel threads measured 280-350 nm in length and stained with the low pH-phosphotungstic acid technique for carbohydrate and with the silver methenamine technique for aldehydes (as did extracellular collagen fibrils). The passage of label from spherical to cylindrical Golgi portions is associated with the reorganization of entangled into parallel threads, which is interpreted as the packing of procollagen molecules. Between 20 and 30 min, prosecretory and secretory granules respectively became labeled. These results indicate that the cylindrical portions of Golgi saccules transform into prosecretory and subsequently into secretory granules. Within these granules, the parallel threads, believed to be procollagen molecules, are transported to the odontoblast process. At 90 min and 4 h after injection, label was present in predentin, indicating that the labeled content of secretory granules had been released into predentin. This occurred by exocytosis as evidenced by the presence of secretory granules in fusion with the plasmalemma of the odontoblast process. It is proposed that pro-alpha chains give rise to procollagen molecules which assemble into parallel aggregates in the Golgi apparatus. Procollagen molecules are then transported within secretory granules to the odontoblast process and released by exocytosis. In predentin procollagen molecules would give rise to tropocollagen molecules, which would then polymerize into collagen fibrils.

Ethnocentrism and Causal Attribution in a South Indian Context

Abstract: Hindu Ss were asked to attribute the behavior of in-group (Hindu) and out-group (Muslim) members performing socially desirable or undesirable acts in terms of internal and external causes for the behavior. Subjects made internal attributions of in-group members performing socially desirable acts and external attributions for undesirable acts. The converse was true for attributions made by the Hindu Ss with respect to the same behavior performed by Muslims. The results were discussed in terms of the importance of attribution theory principles for studying prejudice and the relationship between attitudes and behavior.

What's in a name? A study of how children learn common and proper names.

Abstract: KATZ, NANCY; BAKER, ERICA; and MACNAMARA, JOHN. What's in a Name? A Study of How Children Learn Common and Proper Names. CHmLD DEVELOPMENT, 1974, 45, 469-473. This paper studies the processes whereby small children (17-24 mo.) learn common and proper nouns and learn how English distinguishes between them. Our thesis is that within certain classes of objects (e.g., people), the children first discriminate individuals and then learn their names, whereas among other classes of objects (e.g., spoons) they do not discriminate individuals, and learn names only for the class. These two processes enable the children to learn the syntactic distinction between common and proper nouns. The thesis is supported by two sets of experimental data derived from a total of 80 children.

Migration of glycoprotein from the golgi apparatus to the surface of various cell types as shown by radioautography after labeled fucose injection into rats

Abstract: A single intravenous injection of L-[3H]fucose, a specific glycoprotein precursor, was given to young 35–45 g rats which were sacrificed at times varying between 2 min and 30 h later. Radioautography of over 50 cell types, including renewing and nonrenewing cells, was carried out for light and electron microscope study. At early time intervals (2–10 min after injection), light microscope radioautography showed a reaction over nearly all cells investigated in the form of a discrete clump of silver grains over the Golgi region. This reaction varied in intensity and duration from cell type to cell type. Electron microscope radioautographs of duodenal villus columnar cells and kidney proximal and distal tubule cells at early time intervals revealed that the silver grains were restricted to Golgi saccules. These observations are interpreted to mean that glycoproteins undergoing synthesis incorporate fucose in the saccules of the Golgi apparatus. Since fucose occurs as a terminal residue in the carbohydrate side chains of glycoproteins, the Golgi saccules would be the site of completion of synthesis of these side chains. At later time intervals, light and electron microscope radioautography demonstrated a decrease in the reaction intensity of the Golgi region, while reactions appeared over other parts of the cells: lysosomes, secretory material, and plasma membrane. The intensity of the reactions observed over the plasma membrane varied considerably in various cell types; furthermore the reactions were restricted to the apical surface in some types, but extended to the whole surface in others. Since the plasma membrane is covered by a "cell coat" composed of the carbohydrate-rich portions of membrane glycoproteins, it is concluded that newly formed glycoproteins, after acquiring fucose in the Golgi apparatus, migrate to the cell surface to contribute to the cell coat. This contribution implies turnover of cell coat glycoproteins, at least in nonrenewing cell types, such as those of kidney tubules. In the young cells of renewing populations, e.g. those of gastro-intestinal epithelia, the new glycoproteins seem to contribute to the growth as well as the turnover of the cell coat. The differences in reactivity among different cell types and cell surfaces imply considerable differences in the turnover rates of the cell coats.

Origin, differentiation and renewal of the four main epithelial cell types in the mouse small intestine III. Entero‐endocrine cells

Abstract: The origin, differentiation and renewal of entero-endocrine cells was examined in the duodenum, jejunum and ileum of the mouse using light and electron microscopic radioautography after a single injection or continuous infusion of 3H-thymidine. When s-collidine buffered glutaraldehyde was used for fixation prior to electron microscopic study, all granules in all entero-endocrine cells were spheroidal and, therefore, their shape could not be used to classify the cells into subgroups, as done after fixation in phosphate buffered aldehyde. Thus, the cells were all considered as belonging in a single family. In the light microscope, mitosis is not observed in the entero-endocrine cells identified by iron hematoxylin staining. However, under the electron microscope, a few cells that contain a small number of characteristic granules, some filament bundles and many free ribosomes are in division or are labeled one hour after an injection of 3H-thymidine. These cells are interpreted as young entero-endocrine cells. They are located in the crypt base. They resemble crypt-base columnar cells and are, therefore, suspected of arising from them. Differentiation may be examined by following the fate of the young enteroendocrine cells which are labeled by 3H-thymidine. Within the crypts, these cells acquire a gradually increasing number of granules while losing the ability to divide. The few granules initially present usually have a particulate content and may include a small dense core; but, as differentiation proceeds and granules accumulate, their content is mostly dense and homogeneous. The differentiation of precursor cells into mature entero-endocrine cells takes about two days. Meanwhile, in the same manner as columnar and mucous cells, enteroendocrine cells migrate up the crypt, reach the villus and are lost at the extrusion zone. The turnover time of entero-endocrine cells is estimated to be 3.9 days in duodenum and 4.0 days in jejunum.

Morphological classification of rat incisor ameloblasts.

Abstract: Longitudinal sections through the incisors of the rat show a con- tinuous layer of ameloblasts on the labial surface of the tooth. This layer contains the entire sequence of developmental stages in enamel production. Using 1 µm Epon sections from the upper and lower incisors of 100 gm male rats, the amelo- blast layer was divided into three main zones which were themselves subdivided into regions: (1) Presecretory zone which includes (a) region of ameloblasts facing pulp, itself comprising a posterior portion (upper 172 ± 35 μm; lower 187 ± 37 µm) and an anterior portion (upper 458 ± 28 µm; lower 503 ± 36 µm); (b) region of ameloblasts facing dentin (upper 1210 ± 81 µm; lower 1381 ± 90 µm). (2) Secretory zone, (a) region of inner enamel secretion (upper 2573 ± 141 µm; lower 4274 ± 160 µm); (b) region of outer enamel secretion (upper 1211 ± 60 µm; lower 868 ± 72 µm). (3) Maturation zone (upper 7335 µm; lower 10615 µm), (a) region of postsecretory transition; (b) region of maturation proper, consisting of portions of ameloblasts with striated border and portions of ameloblasts with unmodified apices; (c) region of pigmentation; (d) region of reduced ameloblasts. These regions are readily identified using clear cut morphological criteria. Length measurements made on a group of 40 rats established the reproducibility of this classification. Therefore, this classification will be used as a basis for future studies of cell population kinetics. In a single well orientated longitudinal section through the rat incisor, a continu- ous layer of ameloblasts can be seen on the labial surface of the tooth. This layer contains the entire sequence of develop- mental stages in enamel production. The correct identification and characterization, morphologically and functionally, of each of these developmental stages into definite

Studies of insulin, growth hormone and prolactin binding: ontogenesis, effects of sex and pregnancy.

Abstract: The ontogenesis of specific binding of 125I-labeled insulin, hGH and oPRL was measured in tissues from rat, rabbit and guinea pig. Binding of 125I-oPRL and 125I-hGH was very low in liver membranes from fetal and immature rats. A 9- fold (oPRL) and 3.5-fold (hGH) increase in binding occurred between 20 and 40 days of age with a greater increase in binding in mid and late pregnancy. Binding to male liver membranes was significantly lower at all stages of development. There were no significant changes in the binding of 125I-hGH from fetal through 30 day rabbit liver membranes. Between 30 and 60 days of age, a 6-fold increase in binding occurred, with a further increase in binding during pregnancy. A similar overall pattern was observed with I25I-bGH. The increase in specific binding of 125I-oPRL was more gradual and occurred earlier than for 125I-GH. In the guinea pig, three patterns of 125I-insulin binding with respect to development were observed. Fetal placenta and kidney showed marked increase in specifi...

Properties of a prolactin receptor from the rabbit mammary gland

Abstract: Receptors for human, simian, ovine, bovine and murine prolactin, human growth hormone and human placental lactogen have been identified in plasma-membrane-containing subcellular particles isolated from rabbit mammary glands. The association and dissociation of 125I-labelled prolactin are time- and temperature-dependent processes, both being maximal at 37°C. 125I-labelled prolactin prepared by the enzymic iodination procedure with lactoperoxidase binds better to receptors than does the preparation obtained by using chloramine-t as the oxidizing agent. The binding of 125I-labelled prolactin to receptors is strongly influenced by pH and ionic composition but not by many low-molecular-weight compounds tested, e.g. steroids, nucleotides and several drugs. Receptor activity is sensitive to trypsin and phospholipase C digestion, suggesting that protein and phospholipid moieties are essential for the binding of 125I-labelled prolactin. The binding of 125I-labelled prolactin to receptors is a saturable and reversible process. Scatchard and Lineweaver–Burk analyses suggest that 125I-labelled prolactin has a high affinity for its receptor. Binding of 125I-labelled prolactin to receptors does not result in the destruction of the hormone. Considerable prolactin-binding activity is also observed in subcellular fractions isolated from the adrenal gland, liver, ovary and kidney of the pregnant rabbit, a finding that is consistent with other reported actions of prolactin in these organs.

Dependence in an Interdependent World: The Limited Possibilities of Transformation Within the Capitalist World Economy

Abstract: “Dependence” has become the latest euphemism in a long list of such terms. No doubt its original intent was critical. The term itself emerged out of the “structuralist” theories of Latin American scholars and was meant as a rebuttal to “developmentalist” or “modernization“ theories and “monetarist” policy views. Andre Gunder Frank has traced its intellectual origins and its limitations in a recent combative paper entitled “Dependence is dead; long live dependence and the class struggle.” We live in a capitalist world economy, one that took definitive shape as a European world economy in the sixteenth century (see Wallerstein 1974) and came to include the whole world geographically in the ninteenth century. Capitalism as a system of production for sale in a market for profit and appropriation of this profit on the basis of individual or collective ownership has only existed in, and can be said to require, a world system in which the political units are not co-extensive with the boundaries of the market economy. This has permitted sellers to profit from strengths in the market whenever they exist but enabled them simultaneously to seek, whenever needed, the intrusion of political entities to distort the market in their favor. Far from being a system of free competition of all sellers, it is a system in which competition becomes relatively free only when the economic advantage of upper strata is so clear-cut that the unconstrained operation of the market serves effectively to reinforce the existing system of stratification.

Infiltrating lipomas and angiolipomas revisited.

Abstract: Twenty-seven soft tissue tumors composed of benign adipose tissue are presented featuring extensive local invasion and recurrence. Infiltrating angiolipomas and infiltrating lipomas are two distinct entities with different clinical and histologic features. The surgical approach demands wide local excision assisted by frozen section analysis to assure adequacy of removal. Extensive histologic sampling is mandatory to demonstrate the infiltrative character of the tumor and yet eliminate from consideration liposarcoma with which it may be confused. Although locally recurrent, neither has yet undergone malignant transformation.

Effects of a polychlorinated biphenyl mixture (aroclor 1254) and DDT on biliary thyroxine excretion in rats.

Abstract: Treatment of rats with a polychlorinated biphenyl mixture (Aroclor 1254; PCB) causeda 4- to 5-fold increase in the 3-hr biliary excretion of 125I-thyroxine (T4). In treated rats bile flow was increased and the 125I-T4 bile:plasma ratios (B/Pratios) and biliary clearance rate of plasma 125I-T4 were greatly elevated. The proportion of biliary 125I present as T4-glucuronide was larger in PCB-treated rats. PCB also elevated thyroid 13II uptake andreduced serum PBI concentrations. DDT did not affect the biliary excretion of 125I-T4, but did increase bile flow and the biliary clearance rate of plasma 125I-T4. It also caused a marginal elevation of B/P ratios and increased the proportion of biliary 125I present as T4-glucuronide slightly but significantly. DDT did not affect thyroid 13II uptake or serum PBI concentrations. The effects of PCB were similar to those of the polycyclic hydrocarbon-type of enzyme inducers. The results of DDT-treatment were similar to those produced by the phenobarbital type of inducer...