Biomedical subjects

P Arsenault

Publications and source records attributed to P Arsenault.

13 recordsLinked to original sources

PubMed1991

The successful resuscitation of a hypothermic multitrauma patient.

Accidental hypothermia due to exposure is an infrequent cause of circulatory arrest. A premature diagnosis of clinical death must be avoided in these patients and vigorous attempts at active rewarming are indicated. Extracorporeal circulation in the form of partial cardiopulmonary bypass has been reported as an effective means of rapid, even core rewarming. We wish to report a recent case at Ruby Memorial Hospital in which extracorporeal circulation was used successfully in resuscitating a profoundly hypothermic multi-trauma victim.

Accidents, Traffic↗

PubMed1990

Cell proliferation in developing human stomach.

Cell proliferation during morphogenesis of human stomach was investigated using radioautography and biochemical determinations of [3H]-thymidine incorporation into DNA. Labeling indices in the epithelium, mesenchyme and muscle layer were established on radioautographs and the heights (mm) of the gastric glands were measured between 10 and 17 weeks of gestation. At 11-12 weeks, the appearance of the first pit/gland was noted, and the labeling index ranged from 9.2 to 10.2%. Labeled cells were present at all levels of the stratified epithelium. Between 14 and 16 weeks, the total epithelial labeling index declined sharply (8.1 to 5.4%) with a concomitant increase of the height of the pit/gland structures (0.055 to 0.080 mm). High proliferative activity was also recorded in the mesenchyme and the muscle layer, the labeling indices decreasing between 10 and 17 weeks. The biochemical quantitation of the [3H]-thymidine uptake into the total gastric DNA clearly supported the continuous decrease of the cell proliferation determined by radioautography. Detailed analysis of the epithelium showed that proliferative cells were more numerous at the base of the gland at the earliest stage (11 weeks) but concentrated in the pit/neck regions by 13-14 weeks. As the pit/gland development proceeded (14 to 17 weeks) labeled cells remained more abundant in the pit/neck regions of the gland (10.9%) and were rarely seen on the surface epithelium (2%). The present investigation provides basic quantitative data regarding cell proliferation in developing human stomach, and indicates that the morphogenesis of the gastric glands is correlated with the high proliferative capacity of the pit/neck cells.

Cell Division↗

PubMed1990

Differential effects of epidermal growth factor and hydrocortisone in human fetal colon.

The influence of epidermal growth factor (EGF) and hydrocortisone on the functional development of human fetal colon was studied in organ cultures. Fetal colon (14 to 17 weeks gestation) was cultured for 5 days at 37 degrees C in serum-free Leibovitz L-15 medium alone or supplemented with 1, 10, and 100 ng of EGF/ml or with 50 ng of hydrocortisone/ml of culture medium. The overall morphology of the colonic explants was not altered by the hormonal addition. In the continuous presence of EGF (1, 10, and 100 ng/ml) for 5 days, a significant decrease of [3H]thymidine incorporation into DNA was observed. At the brush border level, the addition of EGF induced a significant drop in sucrase, maltase, and alkaline phosphatase activities. These enzymic modifications occurred between the third and fifth day of culture, whereas variation in DNA synthesis was already evident within 24 h. The addition of hydrocortisone at a dose affecting the small intestine (50 ng/ml) did not significantly influence colonic DNA synthesis nor the digestive enzymic activities. These observations show for the first time that EGF, but not hydrocortisone, influences the proliferation and differentiation of human fetal colonic mucosa.

Cell Division↗

PubMed1989

Cell proliferation during morphogenesis of the human colon.

Cell proliferation during morphogenesis of human colon from 8 to 18 weeks of gestation was investigated using radioautography. The sites of [3H]-thymidine uptake were localized in the epithelium, the mesenchyme, and the muscularis externa. As long as the epithelium was stratified, the proliferative pool was very large, and the highest labeling indices (up to 28%) were found during this period. With the formation of villi, the proliferative pool decreased and focused exclusively in the developing crypts by 14-15 weeks. Between 8 and 11 weeks, the labeling index was similar both in the epithelium and the mesenchyme. By 13 weeks of gestation, the small intestinal cell proliferation pattern (epithelium greater than mesenchyme greater than muscular layer) was established in the fetal colon. The biochemical quantitation of the [3H]-thymidine uptake into the total colonic DNA supported the decreasing cell proliferation pattern determined by radioautography. The present investigation establishes basic quantitative data regarding cell proliferation during a particular developmental phase of the human colon.

Autoradiography↗

PubMed1988

Autoradiographic localization of [3H]-thymidine incorporation in developing human esophagus.

Cell proliferation in the developing human esophagus was investigated by autoradiography using organ culture. The sites of [3H]-thymidine uptake were localized in the epithelium, the mesenchyme, and the muscularis externa of fetal esophageal explants from 10 to 16 weeks of gestation. Proliferating cells were abundant throughout the stratified epithelium at 10 weeks of gestation. Many labeled nuclei in the mesenchyme and the muscular layer were observed. With the development of the stratified columnar ciliated epithelium, a confinement of the proliferating zone in the basal cell layers occurred, and ciliated cells never appeared labeled. The quantitation of proliferating cells showed a labeling index at its highest value between 10 and 12 weeks; this drastically decreased between 12 and 14 weeks' gestation. A similar pattern was noted for the mesenchyme, while the labeling index in the muscularis externa peaked during the 11-14 weeks period. In all fetuses, the highest labeling index was always recorded in the epithelium. The biochemical quantitation of the [3H]-thymidine uptake into the total esophageal DNA clearly supported the continuous decrease of the cell proliferation determined by autoradiography between 10 and 16 weeks of gestation. The present investigation provides for the first time basic quantitative data regarding cell proliferation during a particular developmental phase of the human esophagus.

Cell Division↗

PubMed1988

Biologic effects of epidermal growth factor in human fetal jejunum.

The influence of epidermal growth factor (EGF) on the differentiation and proliferation of human fetal jejunum was studied in organ cultures. Fetal intestine (11-14-wk gestation) was cultured for 5 days at 37 degrees C in serum-free Leibovitz L-15 medium alone or supplemented with 25, 50, and 100 ng EGF/ml culture medium. The addition of hormone did not modify the morphology of the intestinal explants. Biochemical studies revealed that lactase activity was significantly increased with the addition of 50 and 100 ng EGF/ml culture medium. On the other hand, the increase in sucrase, trehalase, and glucoamylase activities that normally occurs during the culture was repressed in the presence of increasing concentrations of EGF. Deoxyribonucleic acid synthesis was significantly decreased after 5 days of culture even in the presence of the lowest EGF concentration used. Concomitantly, the labeling index of the epithelial cells dropped drastically in the presence of EGF. The EGF-induced variation in DNA synthesis was already evident within 24 h of culture, whereas enzymic modifications occurred only between the third and fifth day of culture. The simultaneous addition of EGF and hydrocortisone (50 ng/ml) did not reveal any synergistic action between the two hormones on the hydrolytic activities of the brush border. However, EGF did inhibit hydrocortisone-stimulated DNA synthesis. The present work provides for the first time some basic data on the influence of EGF on brush border hydrolytic activities and on epithelial cell proliferation of human fetal jejunum. These observations strongly suggest that EGF plays an important role in the fetal development of the human gastrointestinal tract.

Cell Division↗

PubMed1987

Maturation of human fetal esophagus maintained in organ culture.

The purpose of this work was to study the human fetal esophagus maintained in organ culture. Esophageal explants from 8 fetuses aged from 12 to 16 weeks of gestation were cultured up to 21 days at 37 degrees C in Leibovitz L-15 serum-free medium. Between 12 and 16 weeks of gestation, the esophagus has a stratified columnar ciliated epithelium, and glycogen aggregates are present in all cell layers. This morphology remains the same up to 5 days in culture. After 7 to 9 days, a vacuolization in the upper half layer occurs, leading to a lifting off of the ciliated layer and a flattening of the subjacent cells. After 15 days of culture, the esophageal epithelium is stratified squamous and the cells are exfoliated at the surface of the explants. Glycogen aggregates are still present in all layers. Islets of ciliated cells resting on the basal cell layers develop within the squamous epithelium. With the extension of the culture period up to 21 days, the general morphology of the epithelium does not change. The ultrastructural features of the newly formed squamous epithelium, with its basal lamina, are similar to that reported for human adult esophageal epithelium. During the course of the culture, the DNA synthesis continues as determined by autoradiography. It is concluded that it is possible to maintain viable human fetal esophagus in organ culture and that an accelerated maturation takes place leading to the formation of the adult esophageal epithelium.

Cell Differentiation↗

PubMed1987

Human fetal colon in organ culture.

Human fetal colon (14-16 weeks gestation) was cultured as explants for 15 days in serum-free Leibovitz L-15 medium at 37 degrees C. The overall morphology of the colonic explants was well maintained throughout the culture period and all epithelial cell types retained their ultrastructural characteristics. The incorporation of [3H]-leucine continued and even increased, reflecting sustained synthesis of proteins. Even though the incorporation of [3H]-thymidine into the total DNA decreased during culture, the synthesis of DNA continued. The sites of [3H]-thymidine incorporation into the different layers of the colonic wall were studied by radioautography. The incorporation of the radioactive precursor occurs mainly in the epithelium and to lesser degrees in the mesenchyme and the muscular layer. Labeled epithelial nuclei were located in the intervillous areas but not on the villi. The labeling index of the epithelial cells remained constant throughout the culture period indicating the preservation of the proliferative capacity of the epithelium. Brush-border hydrolytic activities, namely those of sucrase, maltase, lactase, trehalase, glucoamylase and alkaline phosphatase, were assayed in the colonic tissue. These enzymic activities generally decreased in the tissue and increased in the medium during the course of culture. These observations clearly demonstrate that fetal colon can be maintained viable for at least 15 days in a serum-free medium. Organ culture now provides the opportunity to study the normal function and metabolism of human colon during its development.

Autoradiography↗

PubMed1987

Stimulatory effects of epidermal growth factor on deoxyribonucleic acid synthesis in the gastrointestinal tract of the suckling mouse.

The effects of epidermal growth factor (EGF), cortisone and thyroxine on deoxyribonucleic acid (DNA) synthesis in the esophagus, stomach, small intestine and colon have been studied in suckling mouse. Daily administration of EGF [4 micrograms/g body weight (bw)/day] during 3 days to 8-day-old mice induced a significant increase of the incorporation of [3H]thymidine into DNA in the stomach, the small intestine, and the two halves of the colon. The DNA synthesis in the esophagus remained unaffected by the EGF treatment. The maximal increase of [3H]thymidine incorporation into DNA was observed in the colon, and represented 112%. Daily administration of cortisone acetate (25 micrograms/g bw/day) or thyroxine (1 microgram/g bw/day) during 3 days to 8-day-old mice had no significant influence of the DNA synthesis of any part of the gastrointestinal tract. These results show that EGF is able to affect the DNA synthesis in the stomach, small intestine and colon of suckling mice.

Animals↗

PubMed1987

Cell proliferation in developing human jejunum.

Cell proliferation of the developing human jejunum was investigated by radioautography using organ culture. The sites of [3H]-thymidine uptake were localized in the epithelium, the mesenchyme and the muscularis externa of fetal human small intestinal explants from 8 to 18 weeks of gestation. Proliferating cells were abundant and scattered throughout the stratified epithelium before the appearance of villi. Many nuclei in the mesenchyme and the muscular layer were labeled. With the villi formation and the simplification of the epithelium, there was a confinement of the proliferating zone in the intervillus areas and developing crypts. The quantitation of proliferating cells showed a labeling index at its highest value between 8 and 10 weeks of gestation decreasing gradually up to 18 weeks of gestation at the epithelial and mesenchymal level. In the muscularis externa, the labeling remained more or less constant between 11 and 18 weeks of gestation. The organ culture of intestinal explants for 5 days did not modify epithelial cell proliferation. The present investigation provides for the first time basic quantitative data regarding cell proliferation in the developing human jejunum.

Autoradiography↗

PubMed1985

Explant culture of human fetal small intestine.

Human fetal intestine (10-14 wk gestation) has been cultured as explants in a serum-free Leibovitz L-15 medium for periods up to 9 days. As determined by light microscopy, the overall architecture of the intestinal explant was maintained throughout the culture period. At the ultrastructural level the villus absorptive cells remained tall with well-defined brush border, apical tubular system, and supranuclear and infranuclear accumulations of glycogen. All other epithelial cell types were also preserved. The incorporation of [3H]thymidine and [3H]leucine continued during the culture period, reflecting a sustained synthesis of deoxyribonucleic acid and proteins. The hydrolytic activities of the brush border membrane were established based on data obtained throughout the course of the culture of a large number of intestinal specimens. Sucrase, maltase, glucoamylase, trehalase, lactase, alkaline phosphatase, and gamma-glutamyl transpeptidase activities increased during the 9 days of culture even though different patterns were recorded. These observations clearly established that human fetal small intestine can be maintained in organ culture for at least 9 days in a serum-free medium.

Culture Media↗

PubMed1985

Development of enteropeptidase activity in mouse small intestine: influence of hormones.

The postnatal development of enteropeptidase activity has been examined on mucosal scrapping of the proximal part of the mouse small intestine. The activity was present at birth and remained low during the first 15 days of life. Then it rapidly increased reaching adult level within 2 days. Daily administration of cortisone acetate (25 micrograms X g body weight (bw)-1 X day-1), insulin (12.5 mU X g bw-1 X day-1), or epidermal growth factor (4 micrograms X g bw-1 X day-1) during 3 days to 8-day-old mice induced a premature increase of enteropeptidase. The maximal increase was observed with cortisone treatment, the enzymic activity representing 70% of the adult level. Thyroxine alone (1 microgram X g bw-1 X day-1) had no significant effect on enteropeptidase activity. Hormonal interactions have been evaluated by studying the effects of different hormonal combinations. Finally, cortisone acetate which has a major effect on this activity during suckling period was unable to influence adult small intestinal enteropeptidase activity.

Animals↗

PubMedDate not supplied

Epidermal growth factor does not act as a primary cue for inducing developmental changes in suckling mouse jejunum.

The direct influence of epidermal growth factor (EGF) on the differentiation and proliferation of small intestine was studied in organ culture. Eight-day-old mouse small intestine was cultured during 2 days in serum-free Leibovitz L-15 medium alone or supplemented with EGF (50, 100, and 500 ng/ml) either at room temperature or at 37 degrees C. Brush border membrane hydrolytic activities, namely, sucrase, lactase, glucoamylase, trehalase, maltase, and alkaline phosphatase, were assayed in the intestinal tissue as well as in the culture medium. None of the brush border enzymic activities was affected by the addition of EGF to the culture medium. This lack of effect is not temperature dependent since it occurred both at room temperature and at 37 degrees C. The addition of hydrocortisone (10(-6) M) to the culture medium induced the appearance of sucrase activity and increased the activity of the other brush border enzymes. The simultaneous addition of EGF with hydrocortisone did not influence the response of the intestinal explants to hydrocortisone. The deoxyribonucleic acid (DNA) content was determined while DNA synthesis was evaluated by the incorporation of (3H)-thymidine. The addition of EGF did not affect DNA content or (3H)-thymidine incorporation into DNA either at room temperature or at 37 degrees C. The EGF binding to epithelial cells did not significantly vary throughout the culture period and a down-regulation process occurred in presence of EGF. These observations strongly suggest that EGF does not act as a primary cue for inducing developmental changes in suckling mouse small intestine. It is proposed that EGF induces a systemic reaction in vivo that then influences the neonatal small intestine.

Animals↗