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PubMed1990

Elderly Hispanic migration in the United States.

The specific aim of this study was to extend the analysis of migration patterns to Hispanics (Mexican, Cuban, Puerto Rican, and Other Hispanic) over the age of 60. The 1980 Census public use sample provided the data for this study, which was structured by four research expectations derived from features of the Hispanic population and from migration concepts. First, because of population growth, migration from abroad was expected to be heavy, and about half came from abroad. Second, because of the pattern of Hispanic population concentration and the different settlement patterns of the four subgroups, a relatively small migration system with distinct subsystems for the four nationality groups was expected and found. Florida is the major ethnomagnet. Third, traditional family values, as reflected in dependent living arrangements, were expected to be more prevalent among migrants from abroad, and they were. Finally, returning to one's state of birth was highest among Mexican interstate migrants, as expected.

Aged↗
PubMed1981

Periodic contractions of the canine gallbladder during the interdigestive state.

Interdigestive contractile activity of the gallbladder, the stomach, and the duodenum was measured by means of chronically implanted force transducers in five conscious dogs. During the interdigestive state, contractions of the gallbladder were identified to be closely associated with the initial period of phase II of the interdigestive migrating contractions (IMC) in the duodenum. The mean contractile force of the gallbladder during this phase was 6.5 +/- 0.77 g, which corresponded to approximately 80% of the force of the postprandial contractions. When the duodenum exhibited phase II contractions, the gallbladder had already returned to the resting level. Intravenous infusion of synthetic motilin induced IMC in the stomach and duodenum and during the initial period of motor response of the duodenum reproduced contractions in the gallbladder that were identical to the natural contractions as to their period and pattern. We cannot yet ascribe the interdigestive contractions observed in the gallbladder to the direct action of motilin, but the present study clearly indicates that the gallbladder contracts even in the interdigestive state, and the contractions are associated with the phase II contractions in the duodenum.

Animals↗
PubMed1994

A potent stimulator of small intestinal cell proliferation extracted by simple diffusion from intact irradiated intestine: in vitro studies.

The epithelium lining the small intestine is one of the most rapidly proliferating body tissues yet it rarely develops cancers. The proliferation, migration and differentiation of the stem cell progeny appears to be under very strict control. After 8 Gy gamma irradiation the murine epithelium contains surviving stem cells from which the epithelium rapidly and effectively regenerates, presumably in response to stimulatory signals, and then returns to steady state conditions after overshoots in proliferation. Here we describe the isolation and preliminary characterisation in vitro of a potent stimulatory extract obtained by diffusion from intact murine small intestine, post-irradiation. In addition to in vivo responses the extract stimulates intestinal epithelial lines very effectively, most notably the rat IEC 18 line where it can replace the serum requirement. The extent of the induced increase in proliferation could not be reproduced by any other single growth factor tested. Preliminary evidence suggests the extract contains either a potent stimulatory cocktail of factors or a novel intestinal growth factor(s).

Animals↗
PubMed1993

The wound healing process.

The field of wound repair continues to grow at an astounding pace. In this review we have discussed both the basic science and the clinical aspects of wound healing. The basic science section details the three phases of wound healing. The inflammatory phase is marked by platelet accumulation, coagulation, and leukocyte migration. The proliferative phase is characterized by re-epithelialization, angiogenesis, fibroplasia, and wound contraction. Finally, the remodeling phase takes place over a period of months, during which the dermis responds to injury with the production of collagen and matrix proteins and then returns to its preinjury phenotype. The second part of this review outlines selected practical clinical aspects of wound repair. That section is subdivided into acute and chronic wounds. We describe the difference between primary and secondary intention healing and discuss factors that affect healing in both. We also describe our systemic approach to dealing with patients with chronic wounds and present our problem-oriented treatment program based on the cause of the chronic wound.

Cell Division↗
PubMed2005

Multiple sclerosis in Newfoundland and Labrador--a model for disease prevalence.

BACKGROUND: Newfoundland and Labrador, Canada, have been almost exclusively populated by immigrants from southwest England and southeast Ireland. The province's population grew largely by natural increase from 20,000 people in 1835 to half a million at present. Very little interregional migration occurred within the province. This uniquely-populated region and its subsequent founder effect provide the basis to develop models of disease prevalence. OBJECTIVES: To develop a model for the regional prevalence of multiple sclerosis (MS), accounting for settlement patterns and geographic location (latitude). METHODS: All living MS patients with confirmed addresses (438 patients) in the province were mailed a survey requesting their place of birth. Regional prevalences were calculated from a 75% rate of return of the survey. Theoretical regional prevalences were proportionally calculated from the source prevalences of southwest England, southeast Ireland, Scotland and the Channel Islands based on settlement patterns. These theoretical regional prevalences were corrected for geographical variations of latitude based on observations in the United Kingdom. Theoretical and actual regional prevalences were compared. RESULTS: When actual regional prevalences were compared with theoretical prevalences, very little variation was noted, especially after correcting for variation in latitude. CONCLUSION: A regional variation in MS prevalence is noted in the island portion of Newfoundland and Labrador. This regional variation can be modeled by using both migration patterns and latitudinal position. This model demonstrates that the prevalence of MS is influenced by both genetic and environmental contributions.

Emigration and Immigration↗
PubMedDate not supplied

The determinants and consequences of female migration in Thailand.

Female migration in Thailand, especially from rural areas to the Bangkok Metropolis, is an important migratory phenomenon which leads to an unfavorable population distribution. Generally the migration level in Thailand is low but many women from the rural areas, especially from the Northeast Region, move to Bangkok Metropolis to seek work. Findings reveal that the majority of migrants are young, single women. Women migrants find it relatively easy to participate in the Bangkok labor market. Service work is the main source of employment. For the temporary migrants, it was found that those from the Northeast Region tend to return to their hometown in higher proportion than those from other regions. This was particularly so among young women migrants.

Age Factors↗
PubMed1979

Assessment of host immune status during progressive growth and after excision of DNA virus (simian virus 40) tumors in hamsters: comparison of tumor-specific and tumor-unrelated parameters of immune responsiveness.

The kinetics of cell-mediated immunity to simian virus 40 (SV40) tumor-specific transplantation antigen (TSTA) were compared to the kinetics of tumor-unrelated parameters of immune responsiveness in the assessment of the immune statuses of inbred MHA/SsLAK hamsters during the course of progressive syngeneic SV40 tumor growth and after tumor excision. With the use of the tumor cell neutralization test in vivo and the macrophage migration inhibition assay in vitro, specific cellular immunity to SV40 TSTA was detected by 4 days after tumor cell inoculation, when the tumor was small. This tumor-specific immune response was no longer detected at 7 days after tumor cell inoculation, when the tumor had reached a mean diameter of 12.5 mm, but it returned by 14 days after surgical excision of the tumor. The patterns of host responsiveness to mitogens in spleen cells derived from tumor-bearing animals or from tumor-excised animals generally showed little or no correlation with the kinetics of tumor-specific cellular immunity. The kinetics of the humoral immune response to murine erythrocytes, as determined by hemagglutination assays, correlated much more closely with the kinetics of tumor-specific immunity than did the responses to mitogens. IgG antibody (T-dependent) responses were more affected by progressive tumor growth than were IgM antibody (T-independent) responses. The data suggest that results of tests with the use of tumor-unrelated parameters of immune responsiveness for the assessment of the immune status of cancer patients should be interpreted with caution.

Animals↗
PubMed1993

Modulation of human microvascular endothelial cell bioenergetic status and glutathione levels during proliferative and differentiated growth.

During angiogenesis, formerly differentiated human microvascular endothelial cells (HMECs) return to a proliferative growth state. Many fundamental questions regarding HMEC function, such as how HMECs adapt to changes in bioenergetic requirements upon return to proliferative growth, remained unanswered. In this study, we evaluated whether modifications in HMEC bioenergetic profiles and glutathione (GSH) levels accompanied the cellular transition between differentiated and proliferative growth. To provide insight into the continuum of cellular adaptations that occur during this transition, we used a method recently developed in our laboratory that induces a state of morphological and functional predifferentiation in HMECs. Cellular morphology, in conjunction with flow cytometric DNA analyses and HMEC functional assays (the directed migration and intercellular association involved in microtubule formation) were employed to validate the HMEC culture state of growth. Analysis of the HPLC nucleotide profiles disclosed several findings common to all culture growth states. These uniform findings, e.g., cellular energy charges > 0.90, and highly reduced redox states, revealed that cultured HMECs maintain high rates of oxidative metabolism. However, there were also significant, culture growth state related differences in the nucleotide profiles. Proliferative HMECs were shown to possess significantly higher (relative to both large vessel endothelial cells, and differentiated HMECs) levels of GSH and specific nucleotides which were related with a return to the active cell cycle-ATP, GTP, UTP, and CTP, and NADPH. Further, the nucleotide profiles and GSH levels of the predifferentiated HMECs were determined to be intermediate between levels obtained for the proliferative and differentiated HMECs. The results of this study demonstrate that the capacity to modulate their cellular bioenergetic status during growth state transitions is one of the adaptations that enable HMECs to retain a growth state reciprocity. In addition, our findings also show that HMECs, especially during the proliferative growth state, are biochemically distinct from endothelial cells harvested from large vessels, and therefore suggest that HMECs are the cells of choice to employ when studying diseases that affect the human microvasculature.

Adolescent↗
PubMed1999

Vascularization of human glioma spheroids implanted into rat cortex is conferred by two distinct mechanisms.

Aim of this study was to develop and characterize an applicable in vivo model to investigate angiogenesis of human gliomas. An established glioblastoma spheroid model was used to investigate the neovascularization of a standardized avascular solid tumor mass. Spheroids of two human glioma cell lines were labeled with an in vivo fluorescent dye. Single spheroids were implanted into the cortex of athymic rats. After 1, 3, 7, 14, and 21 days, brain sections containing the spheroid were immunostained for endothelial cells or vascular endothelial growth factor (VEGF). The dye-stained glioma spheroid and the endothelial cells were visualized by confocal microscopy. Two distinct mechanisms of tumor vascularization could be observed. (1) "Classical" angiogenesis with new vessels sprouting from existing host vessels into the spheroid was seen. (2) Individual endothelial cells were found to migrate towards and into the center of the spheroid where they coalesced to form new vessels. This process occurred as early as 24 hr after spheroid implantation. Spheroid vascularization was accompanied by an increase of VEGF expression, which peaked 7 days after implantation and returned to normal patterns by 14-21 days. Besides the "classical" angiogenesis by angiogenic blood vessels, the recruitment of individual endothelial cells seems to be an additional mechanism in early glioma vascularization. Our model proves to be a reliable, reproducible system to study in vivo angiogenesis of human gliomas.

Animals↗
PubMed1993

Cbr, an algal homolog of plant early light-induced proteins, is a putative zeaxanthin binding protein.

The cbr gene, previously cloned from the unicellular green alga Dunaliella bardawil, is transcriptionally and translationally activated in parallel to accelerated carotenogenesis in response to light stress conditions. The product of cbr, structurally similar to Elips (early light-induced proteins of higher plants), is associated with a minor light harvesting complexes of photosystem II component (Levy, H., Gokhman, I., and Zamir, A. (1992) J. Biol. Chem. 267, 18831-18836). This study examines the relationship between the induction of Cbr and another plant response to light stress, the deepoxidation of violaxanthin to zeaxanthin. A parallel between the two processes was observed in cells exposed to high light, starved for sulfate, or treated with norflurazon, a herbicide inducing photooxidative damage by inhibiting de novo carotenoid biosynthesis. When highly illuminated cells were returned to normal light, Cbr decayed in parallel to the reepoxidation of zeaxanthin to violaxanthin. Evidence for the physical association of Cbr and zeaxanthin was provided by nondenaturing gel electrophoresis. In cells transferred from low to high light, zeaxanthin was associated with the faster migrating of two electrophoretically resolved fractions of light harvesting complexes of photosystem II that also contained Cbr. In cells growing under normal light, violaxanthin was bound equally to the two fractions. Based on these results we propose that Cbr/early light-induced proteins bind zeaxanthin to form photoprotective complexes within the light-harvesting antennae.

Carotenoids↗
PubMed1976

Changes in spleen histology in response to antigenic stimulation in the snapping turtle, Chelydra serpentina.

Proliferative and migratory changes of lymphoid cells in the spleen were observed in turtles stimulated with KLH and maintained at 30 degrees C. Small foci of pyroninophilic lymphoblasts were first seen in the white pulp at about day 5. Progressive enlargement of these centers continued and peaked by days 8-12. By days 15-20 the white pulp returned to a normal (unimmunized) state, while the number of pyroninophilic cells, primarily plasma cells, increased markedly in the red pulp. At days 22-25, the number of plasma cells returned to normal levels and the spleen appeared normal for the remainder of the 60 day observation period. These events suggest that at 30 degrees C, the turtle is capable of a strong and prompt proliferative response in the white pulp sheaths, followed by migration and differentiation of lymphoblasts into plasma cells, in the red pulp. Observations of pyroninophilic cells in sinuses, venules and veins of the spleen and a concomitant depletion of cells in red pulp, further suggest a migration from the spleen to other sites. Following a second antigenic challenge, at day 60, no significant histological changes were observed at 30 degrees C. Nor were any changes observed following primary or secondary antigenic challenge, in animals maintained at 10 degrees C. These findings are discussed with regard to immunological memory and low temperature immunosuppression in ectothermic vertebrates.

Animals↗
PubMed1976

Characterization of macrophage migration inhibitory factor activity produced in vivo by a cell-mediated immune reaction in the guinea pig.

Peritoneal fluid from the abdominal cavities of guinea pigs having delayed hypersensitivity to horseradish peroxidase (HRPO) was obtained by a lavage technique before and after i.p. challenge with antigen. Macrophage migration inhibitory factor (MIF) and macrophage chemotactic factor activities were measured in peritoneal fluids from each animal. Chemotactic activity for macrophages was maximal 24 hr after i.p. challenge and was absent thereafter. MIF activity was maximal in peritoneal fluid 24 to 48 hr after challenge. Macrophages were present in greatest numbers in peritoneal fluid 24 hr after challenge and returned almost to control levels at 48 hr. Macrophages in 48-hr fluid were larger and exhibited more intense cytoplasmic staining for nonspecific esterases when compared to those in 0-hr fluid. The m.w. of MIF obtained from culture supernatants of HRPO-stimulated guinea pig lymphocytes and 48-hr peritoneal fluid were found to be virtually identical, 58,000 and 54,000 daltons, respectively. MIF from these in vitro and in vivo sources were similarly resistant to heating at 56 degrees C for 30 min but were both destroyed by incubation with isoluble trypsin.

Animals↗
PubMed1985

Platelet-derived growth factor and heparin-like glycosaminoglycans regulate thrombospondin synthesis and deposition in the matrix by smooth muscle cells.

Platelet-derived growth factor (PDGF), a smooth muscle cell (SMC) mitogen, and heparin-like glycosaminoglycans, known inhibitors of SMC growth and migration, were found to regulate thrombospondin synthesis and matrix deposition by cultured rat aortic SMC. The synthesis and distribution of thrombospondin was examined in growth-arrested SMCs, in PDGF-stimulated SMCs, and in heparin-treated SMCs using metabolic labeling and immunofluorescence techniques. Thrombospondin synthesis in response to purified PDGF occurred within 1 h after addition of growth factor to growth-arrested SMCs, peaked at 2 h, and returned to baseline levels by 5 h. The induction of synthesis of thrombospondin by PDGF was dose dependent, with a maximal effect observed at 2.5 ng/ml. Actinomycin D (2 micrograms/ml) inhibited thrombospondin induction by PDGF, suggesting a requirement for new RNA synthesis. In the presence of heparin and related polyanions, the incorporation of thrombospondin into the SMC extracellular matrix was markedly reduced. This effect was dose dependent with a maximal effect observed at a heparin concentration of 1 microgram/ml. Heparin did not affect the ability of SMCs to synthesize thrombospondin in response to PDGF. We interpret these data to suggest a role for thrombospondin in the SMC proliferative response to PDGF and in the regulation of SMC growth and migration by glycosaminoglycans.

Animals↗
PubMed1987

Disruption of the jejunal migrating motor complex by gastric distension and feeding in the dog.

1. The jejunal motor response to gastric distension has been quantified in the conscious dog and compared with that of feeding in order to determine the role of the physical bulk of a meal in the conversion from fasted to fed motor activity. 2. In six dogs gastric distension abolished the cyclical migrating motor complex (m.m.c.) and evoked a pattern of continuous irregular jejunal motility similar to that seen postprandially, but only after a latency of 21.5 +/- 2.7 min compared to that of 7.1 +/- 1.2 min for the response to feeding. Computer analysis of distension and fed jejunal motility revealed similar distributions of intervals between contractions and contraction amplitudes with comparable mean values for both. 3. In two dogs with antrum and corpus surgically divided distension of the corpus had a similar effect on jejunal motility although the latency to both distension and feeding were considerably less. 4. By varying the period of distension it has been possible to control accurately the duration of the jejunal motor response and so assess its effectiveness in disrupting the timing of the m.m.c. The return to m.m.c. cycling following deflation was independent of preceding complexes. The occurrence of the post-distension activity front was closely related to the act of deflation itself (R = 0.94) following a latency of 26.2 +/- 2.1 min (n = 39). 5. It is concluded that the bulk of a meal contributes significantly to the early part of postprandial motility and is capable of disrupting the timing of subsequent migrating motor complexes.

Animals↗
PubMed2002

Wounding of bioengineered skin: cellular and molecular aspects after injury.

Skin substitutes are increasingly being used in the treatment of difficult to heal wounds but their mechanisms of action are largely unknown. In this study, using histology, immunostaining, flow cytometry, enzyme-linked immunosorbent assay, and reverse transcription polymerase chain reaction, we determined the response to injury of a human bilayered skin substitute. Meshing or scalpel fenestration of the construct was found to stimulate keratinocyte migration and to decrease proliferation. By 24 h, flow cytometry of the keratinocyte component showed that meshing was associated with a 33% decrease in the number of cells in S phase (p < 0.01). An approximately 2-fold decrease in staining for Ki67, a proliferation marker, was observed with meshing of human bilayered skin substitute. The process of reepithelialization was apparent by 12 h, however, the wounded human bilayered skin substitute was healed by day 3, and a stratum corneum and fully stratified epithelium were re-established by day 4. Reverse transcription polymerase chain reaction analysis and enzyme-linked immunosorbent assays showed that the expression of acute proinflammatory cytokines (interleukins 1alpha, 6, and 8, tumor necrosis factor alpha) peaked by 12-24 h postinjury. The levels of mRNA of certain growth factors (transforming growth factor beta1, vascular endothelial growth factor, insulin-like growth factor 2) but not others (platelet-derived growth factors A and B, keratinocyte growth factor, fibroblast growth factors 1 and 7, transforming growth factor beta3) increased by 12 h and peaked by 1-3 d after injury, returning to normal by day 6. Immunostaining for tumor necrosis factor alpha and transforming growth factor beta1 paralleled these findings by reverse transcription polymerase chain reaction. We conclude that human bilayered skin substitute, as a prototypic bilayered skin substitute, is a truly dynamic living tissue, capable of responding to physical injury in a staged and specific pattern of cell migration, reepithelialization, and cytokine expression.

Cytokines↗
PubMed1997

Recovery of gastrointestinal tract motility and myoelectric activity change after abdominal surgery.

OBJECTIVE: To investigate the relationship between fedstate gastrointestinal tract (GI) function and upper GI myoelectric changes seen after abdominal surgery. DESIGN: Twenty-one adult female mongrel dogs underwent either an open cholecystectomy, a laparoscopic cholecystectomy alone, or a laparoscopic cholecystectomy with peritoneal injury (n = 7 for each group). Bipolar recording electrodes were placed on the antrum and 3 sites of the proximal small intestine to record fasting myoelectric data each morning postoperatively. Solid-phase, technetium Tc 99m gastric emptying studies were performed on postoperative days 1 and 2. Radiopaque markers were ingested just before operation, and the excreted markers were counted using x-ray films of the feces. MAIN OUTCOME MEASURES: Postoperative fasting GI myoelectric activity, gastric emptying, and intestinal transit time. RESULTS: Migrating motor complexes (MMCs) in the small intestine were observed in 33.3% and 75.0% of the dogs on postoperative days 1 and 2, respectively. Gastric dysrhythmias were observed in 23.8% and 45.0% of the dogs on postoperative days 1 and 2, respectively. No relationship between type of surgery and the presence of MMCs or gastric dysrhythmias was noted. Gastric emptying was delayed on postoperative day 1 and was unrelated to the presence of MMCs. Transit time was not significantly delayed in dogs without MMCs on postoperative day 1 compared with that in dogs with MMCs on that day. The presence of gastric dysrhythmias did not affect transit time studies. CONCLUSION: Fasting GI myoelectric activity, including the return of MMCs and the presence of gastric dysrhythmias, does not accurately predict fed-state gastrointestinal GI function following abdominal surgery.

Abdomen↗