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PubMed1985

In vitro modulation of differentiation by calcium in organ cultures of human and murine epithelial tissue.

The differentiation of epithelial tissue in organ cultures of murine buccal mucosa, various human oral mucosa, and human newborn foreskin was found to be dependent on the calcium concentration of the culture media. In low calcium medium (less than or equal to 0.07 mM) epithelial differentiation was inhibited. The original stratifying layers separate and can be removed, producing a destratified explant. Histologically such an explant consists of a dorsal epithelial layer of basal keratinocytes resting on an intact basal lamina with subjacent stroma. At 0.01 mM calcium, the epithelial layer was one to two cells thick whereas at 0.07 mM it could be three or more layers in thickness with the most superficial cells being spread over the underlying cells. In addition to differentiation, keratinocyte migration over the sides of the explant (epiboly) and epithelial proliferation as determined by [3H]thymidine autoradiography were reduced by culture in low calcium medium. Redifferentiation occurs upon return to normal calcium levels (1.8 mM); addition of hydrocortisone to low calcium media was found to facilitate this redifferentiation.

Adult↗
PubMed2005

The postnatal rat aorta contains pericyte progenitor cells that form spheroidal colonies in suspension culture.

Pericytes play an important role in modulating angiogenesis, but the origin of these cells is poorly understood. To evaluate whether the mature vessel wall contains pericyte progenitor cells, nonendothelial mesenchymal cells isolated from the rat aorta were cultured in a serum-free medium optimized for stem cells. This method led to the isolation of anchorage-independent cells that proliferated slowly in suspension, forming spheroidal colonies. This process required basic fibroblast growth factor (bFGF) in the culture medium, because bFGF withdrawal caused the cells to attach to the culture dish and irreversibly lose their capacity to grow in suspension. Immunocytochemistry and RT-PCR analysis revealed the expression of the precursor cell markers CD34 and Tie-2 and the absence of endothelial cell markers (CD31 and endothelial nitric oxide synthase, eNOS) and smooth muscle cell markers (alpha-smooth muscle actin, alpha-SMA). In addition, spheroid-forming cells were positive for NG2, nestin, PDGF receptor (PDGFR)-alpha, and PDGFR-beta. Upon exposure to serum, these cells lost CD34 expression, acquired alpha-SMA, and attached to the culture dish. Returning these cells to serum-free medium failed to restore their original spheroid phenotype, suggesting terminal differentiation. When embedded in collagen gels, spheroid-forming cells rapidly migrated in response to PDGF-BB and became dendritic. Spheroid-forming cells cocultured in collagen with angiogenic outgrowths of rat aorta or isolated endothelial cells transformed into pericytes. These results demonstrate that the rat aorta contains primitive mesenchymal cells capable of pericyte differentiation. These immature cells may represent an important source of pericytes during angiogenesis in physiological and pathological processes. They may also provide a convenient supply of mural cells for vascular bioengineering applications.

Actins↗
PubMed1996

Development of CD4-CD8- alpha beta TCR+NK1.1+ T lymphocytes: thymic selection by self antigen.

Development of CD4-CD8- double negative (DN) alpha beta TCR+ cells were examined by cell transfer experiments using an Ly-5 congenic mouse system. Purified DN alpha beta TCR+ thymocytes injected intrathymically emigrated from the thymus to the spleen. The same cells did not return to the thymus when injected i.v. Similarly, peripheral DN alpha beta TCR+ cells from spleen and liver did not go to the thymus when injected i.v. but migrated to the spleen. These results indicate that DN alpha beta TCR+ thymocytes develop within the thymus and emigrate to peripheral organs. It is thus likely that peripheral DN alpha beta TCR+ cells are at least partly of thymic origin. DN alpha beta TCR+ thymocytes are unique in that they express a natural killer cell marker, NK1.1, which is not found on conventional T cells. We further examined the thymic selection of DN alpha beta TCR+NK1.1+ thymocytes by using an anti-HY TCR-transgenic (tg)/Rag-2(-/-) mouse system with H-2 backgrounds that were negative, positive, or nonselecting for conventional T cells. The number of DNtg TCR alpha beta+NK1.1+ cells was m prominent in male H-2b animals in which conventional T cells are deleted by HY/H-2Db recognition. Fewer DNtg TCR alpha beta+NK1.1+ cells were found in H-2b females (positive selecting background), and almost no DNtg TCR alpha beta+NK1.1+ cells were detected in H-2d animals (nonselecting background). Unlike conventional T cells, DNtg TCR alpha beta+NK1.1+ cells from anti-HY/Rag-2(-/-) H-2b mice express Fc(epsilon)RI(gamma) and CD3zeta as DN alpha beta TCR+NK1.1+ cells from normal C57BL/6 mice. Our results indicate that DNtg TCR alpha beta+NK1.1+ cells are positively selected by self Ag/MHC and emigrate to the peripheral organs.

Adoptive Transfer↗
PubMed2002

Relaxin stimulates bronchial epithelial cell PKA activation, migration, and ciliary beating.

Relaxin is an insulin-like serum protein secreted during pregnancy and found in many tissues, including the lung. Relaxin is reported to stimulate epithelial cell proliferation, but the effects of relaxin on airway epithelium are unknown. We tested the hypothesis that relaxin would stimulate the increased migration of bronchial epithelial cells (BEC) in response to wounding. Using monolayers of BEC in a wound-healing model, relaxin augmented wound closure with maximal closure occurring at 12 hr (1 micro M). Unlike cytokines, relaxin did not stimulate increased BEC interleukin-8 (IL-8) release. Relaxin caused a significant stimulation of ciliary beat frequency (CBF) in BEC. Because protein kinase (PKA) activation increases CBF and relaxin can elevate intracellular cAMP levels, we measured PKA activity in BEC treated with relaxin. Relaxin increased PKA activity 3-4 fold by approximately 4 hr, with a return to baseline levels by 8-10 hr. Relaxin-stimulated PKA activity differs temporally from the rapid (1 hr) beta-adrenergic activation of PKA in BEC. These data suggest that relaxin augments epithelial repair by increasing airway cell migration and CBF via PKA-dependent mechanisms.

Animals↗
PubMed2001

Selective expression of an endogenous inhibitor of FAK regulates proliferation and migration of vascular smooth muscle cells.

Extracellular matrix signaling via integrin receptors is important for smooth muscle cell (SMC) differentiation during vasculogenesis and for phenotypic modulation of SMCs during atherosclerosis. We previously reported that the noncatalytic carboxyl-terminal protein binding domain of focal adhesion kinase (FAK) is expressed as a separate protein termed FAK-related nonkinase (FRNK) and that ectopic expression of FRNK can attenuate FAK activity and integrin-dependent signaling (A. Richardson and J. T. Parsons, Nature 380:538-540, 1996). Herein we report that in contrast to FAK, which is expressed ubiquitously, FRNK is expressed selectively in SMCs, with particularly high levels observed in conduit blood vessels. FRNK expression was low during embryonic development, was significantly upregulated in the postnatal period, and returned to low but detectable levels in adult tissues. FRNK expression was also dramatically upregulated following balloon-induced carotid artery injury. In cultured rat aortic smooth muscle cells, overexpression of FRNK attenuated platelet-derived growth factor (PDGF)-BB-induced migration and also dramatically inhibited [(3)H]thymidine incorporation upon stimulation with PDGF-BB or 10% serum. These effects were concomitant with a reduction in SMC proliferation. Taken together, these data indicate that FRNK acts as an endogenous inhibitor of FAK signaling in SMCs. Furthermore, increased FRNK expression following vascular injury or during development may alter the SMC phenotype by negatively regulating proliferative and migratory signals.

Adenoviridae↗
PubMedDate not supplied

History of migration studies in biological anthropology.

The earliest studies of human biological factors in migration in which a clear research design was employed date back to the early 20th century in the United States. Maurice Fishberg's study of Jewish migrants, published in 1905, antedated the classic study of Franz Boas initiated in 1908. There have been two main approaches. The first approach examined the impact of migration in relation to changing environment and the importance of environmental plasticity. For example, Fishberg reported that migrants had offspring different in stature from themselves and with differences thought to be due to improvements in the environment, although some selection of genetically determined traits was suggested. Subsequently, a number of research designs have been used, ranging from Boas's simple design of sedente (nonmigrant) adults and children compared with first- and second-generation migrants; Shapiro's extension of this study in Japanese migrants to Hawai'i; Goldstein's four-fold comparison of Mexican sedentes and their offspring in Mexico, and migrants to the USA and their offspring in the USA; and Lasker's extension of Goldstein's Mexican study by including comparison of sedentes with returning emigrants. More sophisticated designs were used by Harrison and Baker in examining altitude effects and changes in subsistence and lifestyle during the 1960s through to the 1980s. The second approach has focused on the effect of migration on gene flow. For example, the clinal variation of ABO blood groups in Europe and Australia is generally purported to result from past migration, although increasing random migration for blood groups is likely to eliminate clinal variation. Migration has usually been considered from a spatial (geographic) perspective, but more recent studies have also investigated the impact of social or occupational movement (social mobility) alone, or in combination with geographic migration, and tested whether such movements are selective or random for a number of biological traits.

Adaptation, Physiological↗
PubMed2003

Interferon-gamma induces macrophage migration inhibitory factor synthesis and secretion by tubular epithelial cells.

Macrophage migration inhibitory factor (MIF) promotes macrophage accumulation and leucocyte activation during inflammation. Macrophage migration inhibitory factor is upregulated in intrinsic renal cells in many types of kidney diseases, and has a pathogenic role in rat crescentic nephritis. However, little is known about the factors that regulate the production and secretion of MIF in kidney cells. In this study, we evaluated whether interferon-gamma (IFN-gamma), a cytokine implicated in the development of kidney disease and a potent inducer of MIF production in macrophages, could promote MIF synthesis and secretion from renal tubular epithelial cells. Northern blot analysis detected constitutive expression of MIF mRNA in rat tubular epithelial cells (NRK52E), which increased twofold after a 6-h stimulation with IFN-gamma. Macrophage migration inhibitory factor protein was found only in the cytoplasm of NRK52E cells. Following IFN-gamma stimulation, intracellular MIF in NRK52E cells was rapidly secreted with a maximal reduction of 50% after 20 min, which returned to normal levels after 2-4 h. Rapid secretion of MIF in response to IFN-gamma was also seen in rat mesangial cells. These findings indicate that IFN-gamma induces rapid secretion of MIF by tubular epithelial cells, and suggest that this may be an important mechanism leading to inflammatory cell accumulation and activation during kidney disease.

Animals↗
PubMed1994

Osteolysis associated with cemented total knee arthroplasty. A case report.

Osteolysis induced by particulate debris occurs within 5 years after cementless total knee arthroplasty, but has not been reported to be a problem after cemented total knee arthroplasty. It has been suggested that the bone-cement interface may form a barrier to polyethylene-debris migration, thereby limiting bone loss. The authors have observed osteolysis in a 75-year-old woman 9 years after cemented total knee arthroplasty. An osteolytic area appeared to return to an area of normal bone architecture 3 years after the removal of synovium and particulate debris without implant revision.

Aged↗
PubMed1996

Genotoxicity of vanadium pentoxide evaluate by the single cell gel electrophoresis assay in human lymphocytes.

Vanadium compounds are extensively used in modern industry and occupational exposure to high doses of Vanadium is quite common. In this study, the genotoxicity of vanadium pentoxide (V2O5) was evaluated directly in whole blood leukocytes and in human lymphocyte cultures using the single-cell gel electrophoresis assay (Comet Assay) to detect DNA damage expressed as DNA strand breaks and alkali labile sites. This chemical produces a clear dose-response in DNA migration in whole blood leukocytes and a significative positive effect only with the highest tested concentration in human lymphocyte cultures. After different recovery times the level of DNA damage returned to the control values. These results indicate that V2O5 is capable to induce DNA single-strand breaks and/or alkali-labile damage.

Adult↗
PubMed1996

Short-term changes in the immune system of elite swimmers under competition conditions. Different immunomodulation induced by various types of sport.

This study was designed to investigate changes in the immune system of elite swimmers compared with well-conditioned age- and sex-matched controls in relation to a competition swim (field study). Furthermore, the aim was to reveal possible differences in immune system changes depending on the type of sport performed by comparing with an earlier study of similar design, from the same laboratory that tested elite runners in relation to a competition run. The swimmers were tested before, immediately after and 2 h and 24 h after a competition swim. Lymphocyte subsets (CD5, CD3, HLA-DR, CD4, CD8, CD19, CD3/CD16+56, CD57, CD18, CD16/CD122) all increased after the run, decreased to normal or subnormal levels after 2 h, and returned to normal after 24 h (absolute numbers). The findings were identical for the swimmers and the age- and sex-matched control group. No change in polymorphonuclear granulocyte migration was found. The lymphocyte proliferative responses decreased 2 h after the exercise. No changes were seen in plasma cytokine levels (interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-alpha) in relation to exercise, but significantly lower baseline values for IL-6 were observed in the swimmers. An increase in total natural killer cell activity immediately after exercise, followed after 2 h by a decrease, was seen in both swimmers and controls. Finally, no complement activation was detected. Compared with an earlier study of elite runners, differences were seen in granulocyte chemotactic response, TNF-alpha plasma activity and the lymphocyte proliferative response to mitogen. These differences might be explained by the degree of immune system activation following muscle damage during exercise, inducing an increase in cytokines, which are known to activate and modulate both lymphocytes and granulocyte function. Our findings demonstrate identical exercise-induced, immune system changes in elite swimmers and well conditioned controls, and furthermore, the findings suggest that different types of sport performed at maximum intensity induce different immune system changes.

Adolescent↗
PubMed1978

White cell involvement in the inflammatory, wound healing, and immune actions of vitamin A.

Stress or injury-induced phenomena, such as impaired wound healing and immune depression, may be related to impaired function of certain leukocyte populations. Since vitamin A prevents some aspects of stress, we studied its effect on various white cell populations in normal and injured rats. Supplemental vitamin A (150,000 IU/kg chow) to normal rats resulted in marked increases in thymic weight and lymphocytes without any effct on adrenal weight. The basal chow contains 13,700 IU vitamin A per kg. In rats subjected to moderately severe injury (dorsal wounding or unilateral femoral fracture), supplemental vitamin A greatly diminished the thymic involution observed in chow-fed controls and delayed or minimized the accompanying adrenal hypertrophy. In uninjured rats, supplemental vitamin A induced in three to four days a temporary circulatory leukocytosis characterized by lymhocytosis, monocytosis, and a relative neutropenia. These changes in the blood picture persisted one day after femoral fracture. On the second and third day postfracture the lymphocyte and neutrophil values returned to normal while the monocytosis persisted. Polyvinyl alcohol sponges implanted next to the fracture site demonstrated that supplemental vitamin A consistently increased the number of white blood cells migrating into the wound area and showed significantly larger numbers of monocytes/macrophages. These data suggest that vitamin A influences the numbers and nature of white cells involved in immune, inflammatory, and wound healing processes. In addition to the known antiglucocorticoid activity of vitamin A, these effects may represent a direct beneficial action of dietary vitamin A supplements for stressed and injured animals.

Adrenal Glands↗
PubMed1986

Late results of excision of the radial head for an isolated closed fracture.

A retrospective study was undertaken of twenty patients with a Mason type-II and sixteen patients with a Mason type-III closed fracture of the radial head who had excision of the radial head. The average length of follow-up was 16.4 years (range, three to twenty-seven years) and the average age of the patients at operation was forty-two years (range, eighteen to seventy-five years). Thirty-one patients (86 per cent) were satisfied with the results, and thirty-four (94 per cent) returned to their preoperative occupations. Only three patients lost 30 degrees or more of flexion of the elbow or of pronation or supination of the forearm. A measurable proximal migration of the radius of more than one millimeter was found in eight patients (22 per cent), but no harmful effects of this were found. All of the patients showed osteoarthritic changes on roentgenograms of the elbow that had been operated on, but these did not affect the functional scoring. According to the functional classification that we used, thirty-three (92 per cent) of the patients were able to function satisfactorily in activities of daily living and only three were not. We concluded that if, for any reason, operative treatment is undertaken for these fractures, good functional results can be expected. Nevertheless, because the results of non-operative treatment of Mason type-II fractures, as reported in the literature, have been almost identical to ours, we have adopted a non-operative approach in the last few years.

Activities of Daily Living↗
PubMed2000

Direct measurement of hole transport dynamics in DNA.

Our understanding of oxidative damage to double helical DNA and the design of DNA-based devices for molecular electronics is crucially dependent upon elucidation of the mechanism and dynamics of electron and hole transport in DNA. Electrons and holes can migrate from the locus of formation to trap sites, and such migration can occur through either a single-step "superexchange" mechanism or a multistep charge transport "hopping" mechanism. The rates of single-step charge separation and charge recombination processes are found to decrease rapidly with increasing transfer distances, whereas multistep hole transport processes are only weakly distance dependent. However, the dynamics of hole transport has not yet been directly determined. Here we report spectroscopic measurements of photoinduced electron transfer in synthetic DNA that yield rate constants of approximately 5 x 10(7) s(-1) and 5 x 10(6) s(-1), respectively, for the forward and return hole transport from a single guanine base to a double guanine base step across a single adenine. These rates are faster than processes leading to strand cleavage, such as the reaction of guanine cation radical with water, thus permitting holes to migrate over long distances in DNA. However, they are too slow to compete with charge recombination in contact ion pairs, a process which protects DNA from photochemical damage.

Base Pairing↗
PubMed2000

Role of Fogarty catheter manipulation in management of migrated, nonfunctional peritoneal dialysis catheters.

Peritoneal dialysis (PD) catheter migration to the upper abdomen is not an uncommon cause of catheter failure. We prospectively examined the role of the Fogarty catheter manipulation technique to reposition the PD catheter in the pelvis and regain patency. All patients with PD catheter malfunction caused by migration, confirmed by abdominal radiograph, underwent the same protocol. The patient was placed flat on the back, and the Fogarty was advanced into the PD catheter to a premarked point at which the end of the Fogarty was near the end of the PD catheter. The Fogarty balloon was inflated with 0.5 mL of sterile saline, and manipulation was performed by tugging movements until proper placement of the PD catheter into the pelvis was suspected. Infusion and drainage of dialysate was performed to determine patency. The return of the PD catheter into the pelvis was then confirmed by repeated radiograph. Success rates of Fogarty catheter manipulation, early and late recurrence (remigration < or =90 days or >90 days), and complications were prospectively examined in 232 patients over a 6-year period. Catheter migration occurred in 34 of 232 patients (15% incidence). All patients had curled-end, double-cuffed, non-swan-neck PD catheters. Successful repositioning occurred in 24 of 34 patients (71%). None of the 24 repositioned catheters had early recurrence, and 1 of 24 catheters (4%) had late recurrence. None of the patients had procedure-related peritonitis, bowel perforation, or exit-site trauma. These results show that PD catheter migration is relatively common (15%). The Fogarty manipulation technique is a simple, cost-effective way to prolong PD catheter life and preserve its long-term patency. This eliminates the need for surgical intervention in approximately 70% of patients with PD catheter migration.

Adolescent↗
PubMed1996

Glucose transporter 1 expression is enhanced during corneal epithelial wound repair.

Corneal epithelial wound healing involves a number of metabolically demanding processes such as cell migration and proliferation. The energy for those processes is known to be provided by glycolysis. Thus, it was hypothesized that migrating epithelium would require high levels of glucose to provide a substrate for glycolysis. It is well established that glucose is transported into virtually all mammalian cells by the facilitated glucose transport protein, glucose transporter (GLUT). We sought to investigate the expression of one of the isoforms of glucose transporter, GLUT1, in corneal epithelium after epithelial debridement in the rat. Three-millimeter debridement wounds were made on central rat cornea and allowed to heal from 1 hr to 21 days. To quantitate changes in GLUT1 mRNA and protein levels, whole corneal epithelium was harvested and analysed by reverse transcription-polymerase chain reaction, northern blot, and western blot analysis. GLUT1 protein localization was also observed immunohistochemically. Expression of GLUT1 protein rapidly increased following wounding and was 2.4-fold higher than control at 4 hr post debridement. GLUT1 protein levels continued to increase even after epithelial wound closure (24 hr) and peaked at 2 days post debridement, 5.8-fold higher than control. The increase in GLUT1 protein levels coincided with enhanced GLUT1 mRNA levels (3.7-fold higher than control at 4 hr post debridement). Immunofluorescence microscopy showed increased binding of anti-GLUT1 concentrated in the membranes of the basal cells from limbus-to-limbus until 24 hr post wounding. After 24 hr. binding remained enhanced in the wound area, while binding to the limbal basal cells returned to the control level. In conclusion, the expression of GLUT1 mRNA and protein are rapidly enhanced after wounding. This may allow the increased transport of glucose, providing the metabolic energy necessary for cell migration and proliferation.

Animals↗