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PubMed2006

The alveolar epithelial type I-like cell line as an adequate model for leukocyte migration studies in vitro.

The lung is unique as leukocytes not only migrate into the bronchoalveolar space but also return to the parenchyma and then via the lymphatics to the draining lymph node. The aim of this study was to investigate the migration of leukocytes via an epithelial monolayer in a Transwell system against a chemokine gradient. Rat type I-like R3/1 alveolar epithelial cells were cultivated on a Transwell polyester membrane (pore diameter 3 microm) for 3 days until a monolayer was formed. The tightness of the monolayer was determined by transepithelial transport of horseradish peroxidase. Isolated human and rat peripheral blood mononuclear cells (PBMC) were placed in the upper chamber, and different concentrations of monocyte chemotactic protein-1 (MCP-1) in the lower chamber. The transmigration of PBMC was quantified and investigated by light and transmission electron microscopy. PBMC migrated through the epithelial cell barrier intercellularly as well as transcellularly. The migration of PBMC against the MCP-1 gradient was dose dependent. The results indicate that this model could help in the study of key events involved in chemokine-induced cell migration from the airways into tissue.

Animals↗
PubMed1989

Effect of berberine on myoelectric activity and transit of the small intestine in rats.

The motility of the small intestine in unanesthetized rats receiving berberine sulfate (0.2, 2.0, and 20.0 mg/kg i.p.) was investigated. Motility was determined by two methods: myoelectric activity was monitored with indwelling bipolar electrodes, and intestinal transit was measured by the movement of radiochromium (Na51CrO4). The 20.0-mg/kg dose caused a marked inhibition of spike activity for 21.8 +/- 7.0 min and disrupted activity fronts of the migrating myoelectric complex for 212.3 min. Berberine, 2.0 mg/kg i.p., disrupted migrating myoelectric complexes for 64.6 min but spike inhibition was not observed. Transit of the small intestine was significantly (p less than 0.001) delayed at 15 and 100 min after the highest dose of berberine. Naloxone blocked the spike inhibition noted with 20.0 mg/kg of berberine but failed to improve transit. Phentolamine blocked spike inhibition and was associated with a significantly earlier return of activity fronts of the migrating myoelectric complex. Animals pretreated with this antagonist tended toward a higher geometric center in transit studies than those injected with berberine alone. Berberine was also administered by various routes (intraperitoneal injection, intravenous injection, orogastric gavage, and intraluminal injection). An intraperitoneal injection was 10-fold more potent than an intravenous injection. Orogastric gavage and intraluminal administration of berberine did not alter intestinal motility. In summary, berberine sulfate significantly inhibits myoelectric activity and transit of the small intestine. This appears to be partially mediated by opioid and alpha-adrenergic receptors. The antidiarrheal properties of berberine may be mediated, at least in part, by its ability to delay small intestinal transit.

Administration, Oral↗
PubMed1981

The migratory properties of indium-111 oxine labelled lymphocytes in patients with chronic lymphocytic leukaemia.

These studies describe the application of a new method for following the migration of autologous lymphocytes in normal subjects and patients with chronic lymphocytic leukaemia (CLL). There is evidence that Indium 111 oxine is a reliable radioactive cell label for in vivo studies of lymphocyte traffic in man. In normal subjects, where 60-70% of the lymphocytes labelled are T cells, the results are different from those of previous workers. The lymphocytes leave the blood initially but later return to it. It is believed that this is due to the reappearance of cells which at first entered the spleen. It is suggested that the difference between these data and those of Hersey (1971) is due to the failure of lymphocytes in the latter studies to return to the blood after primary migration. In CLL no such reappearance in the blood is seen and the lymphocytes do not leave the spleen in significant numbers over 48 h. This suggests that CLL B cells either do not recirculate through spleen or that their transit time is greater than 48 h. Bone marrow localization in CLL patients is greater than in the normal subjects, suggesting that either a larger proportion of the neoplastic B lymphocytes enter this compartment or their transit time through it is longer than the transit time of a normal T cell predominant population. Localization in normal-sized lymph nodes in patients with CLL is less than that in the lymph nodes of normal subjects. This may possibly be explained by the greater propensity of T lymphocytes to enter lymph nodes than B lymphocytes, or by the altered migratory properties of CLL B lymphocytes as compared with normal B cells.

Adult↗
PubMedDate not supplied

Morphine stimulates iNOS expression via a rebound from inhibition in human macrophages: nitric oxide involvement.

We have previously demonstrated that exposure of human macrophages to morphine results in transient inhibition of cell migratory behavior and adoption of an inactive conformation followed by a return from inhibition resulting in a significant increase in migration velocity and number of activated cells. In the current report, we demonstrate that the return to activation is nitric oxide dependent and inhibited by prior exposure to the opiate antagonist, naloxone. Exposure of macrophages to morphine for 6 hours resulted in a marked inhibition of cell activity and shift of the cell confirmation from amoeboid to round. The inactivation period lasted approximately 2 hrs and was followed by a period of hyperactivity. Incubation of macrophages with naloxone, prior to addition of morphine, inhibited both inactivation and hyper activation phases whereas, naloxone administration just prior to the hyper activation phase did not affect subsequent hyper activation. Morphine acutely stimulates the transient release of nitric oxide (NO) resulting in subsequent macrophage rounding and inactivation. Prolonged observation of the cells revealed another phase of NO release 12 hours following initial morphine exposure that was characterized by prolonged NO production. These data are consistent with acute constitutive NO synthase activation and inducible NO synthase activation following prolonged morphine exposure. Release of NO and changes in cellular activation mediated by morphine was abrogated by NOS, or morphine inhibitors, added prior to morphine exposure. In contrast, NOS, or morphine inhibitors, added during the inhibitory phase had no impact on the subsequent hyper activation phase. It did, however, have an impact on the hyper activation phase when added prior to morphine. These data demonstrate that morphine is capable of induction of both cNOS and iNOS coupled NO release that regulates the macrophage activation state. This may provide insight into the functioning of morphine following periods of trauma or stress when the levels of the opiate increase and, subsequently, inflammatory function is markedly altered.

Journal Article↗
PubMedDate not supplied

Quantitative characterization of cell invasion in vitro: formulation and validation of a mathematical model of the collagen gel invasion assay.

An in vitro assay proposed to systematically characterize and compare cell invasion under different conditions is the collagen gel invasion assay where cells, initially seeded onto the surface of a type I collagen gel, penetrate the surface and migrate within the gel over time. Using simplifying assumptions about cell transport across the gel surface and migration within the gel, we formulate and solve a mathematical model of this assay which predicts the resulting cell distribution based on three phenomenological parameters characterizing the ability of cells to penetrate the gel surface interface, migrate randomly within the gel, and return to the gel surface. An index of cell invasiveness is defined based on these parameters that reflects the overall ability of cells to transport across the gel surface interface, that is, invade the gel. Cell concentration profiles predicted by the model correspond well to measured profiles for murine melanoma cells invading gels supplemented with extracellular matrix proteins fibronectin and type IV collagen as well as unsupplemented gels, allowing these parameters to be estimated by a nonlinear regression fit of the model solution to the measured profiles. Our analysis suggests that type IV collagen and fibronectin primarily modulate cell transport across the gel surface interface rather than migration within the gel. Further, we validate the key model assumptions and obtain independent, direct estimates of model parameters by time-lapse video microscopy and digital image analysis of cell penetration of the gel surface and migration within the gel during the assay.

Algorithms↗
PubMed1994

The wax and wane of interstate migration patterns in the U.S.A. in the 1980s: a demographic effectiveness field perspective.

The author analyzes the structure of temporal changes in U.S. internal migration over the period 1980-1988 using data from matched income tax returns. "A number of hypotheses are explored about how in-migration and out-migration fields wax and wane, thereby giving rise to the overall shifts in demographic effectiveness measured over the period. The results highlight the characteristics of recent (1980-88) shifts in U.S. internal migration patterns including net migration reversals from strong net in-migration to strong net out-migration for states with significant energy sectors, the stanching of net out-migration from many states of the American manufacturing belt, the turnaround to net in-migration for all of northern New England, and the continuance of highly effective net in-migration to the sunbelt states of Florida, Arizona, and Nevada."

Americas↗
PubMed2005

For work and for school: internal migration of Canada's rural nurses.

Using data from the Registered Nurses Database and a recently conducted national survey, this study examined the internal migration patterns of Canadian-educated rural RNs. Inter-provincial migration rates, ranging from 11% to 27% depending on the database used, mask much wider variations in sub-provincial movement rates, which are particularly relevant when considering the provision of nursing services in rural and remote communities. Rural RNs are more likely to migrate if they are female, older, working in nursing stations, and living in remote communities. A majority of RNs whose migration is associated with going to school after their initial nursing education do not return to the jurisdiction where they were first registered. Targeted migration studies are needed to fully understand both the detailed patterns and the predictors of such movements in order to better assess recruitment and retention policies and to enhance our overall health human resources planning models.

Adult↗
PubMed1993

AIDS in Nicaragua: epidemiological, political, and sociocultural perspectives.

The AIDS epidemic in Nicaragua is several years behind that in the United States and neighboring countries of Central and South America. A combination of events, including the isolation caused by the war of the U.S.-backed Contra army against the Sandinista government, the complete economic embargo imposed on Nicaragua by the United States in 1985, self-sufficiency for blood products, and a low rate of recreational injectable-drug use, have contributed to this situation. Since the Sandinistas were defeated in the general election of 1990, people have returned to Nicaragua from areas where HIV is more prevalent, such as Honduras and the United States. It is probable that many HIV-infected persons have now entered the country. Because of the high rates of sexually transmitted diseases and cultural factors such as "machismo," HIV is likely to spread rapidly by heterosexual transmission, unless effective, culturally appropriate education and sexually transmitted disease prevention programs are implemented now.

Acquired Immunodeficiency Syndrome↗
PubMed1980

Inhibition of leukocyte locomotion by tocainide, a primary amine analog of lidocaine: at study with 111indium-labeled leukocytes and scanning electron microscopy.

The ability of tocainide (a primary amine derivative of lidocaine, 2-amino 2, 6-propionoxylidide) to inhibit leukocyte adhesion to and invasion of canine jugular veins was investigated. Leukocyte adhesion and migration were quantitated by use of 111indium-labeled leukocytes, and the morphologic characteristics of leukocytes and vessel lumen were studied by scanning electron microscopy. The morphologic characteristics of adhering and migrating 111indium-labeled leukocytes were similar to leukocytes that had not been manipulated, thus establishing their suitability for use as a marker for flammation. Exposure of leukocytes to 200 micrograms. per ml. of tocainide in autologous plasma in vitro inhibited adhesion and migration by 68 per cent. When labeled leukocytes were returned to the donor and exposed to intravenously infused tocainide the extent of reduction in adhesion and migration depended on whether tocainide infusion was started before or after neck dissection. Inhibition was only 46 per cent when dissection and injection of 111indium-labeled leukocytes preceded the start of infusion of tocainide but was 87 per cent when tocainide infusion was started before dissection and injection of leukocytes. The plasma level ranged from 25 to 47 microM over the 3 hour, 20 minute-infusion period, being 35 to 40 microM for the last hour. Migration of leukocytes across interendothelial junctions and their accumulation between the endothelial sheet and the basement membrane caused extensive damage to the endothelial lining of these veins. This was reduced when leukocyte migration was reduced. These observations suggest that the leukocyte-induced damage occurring in some sterile inflammations might be reduced by the use of local anesthetic drugs.

Anilides↗
PubMed1975

Diapause in Ornithomya biloba Dufour (Diptera: Hippoboscidae) parasitic on fairy martins in South Australia.

A pupal diapause in Ornithomya biloba gives the parasite a life cycle that is well adapted to the migratory life cycle of its host, Petrochelidon ariel (Gould). The fairy martins breed in colonial mud nests to which they return each spring and abandon when they migrate during late summer and autumn. The parasites spend the summer as diapausing puparia in the abandoned nests. Diapause development is completed during winter and the adult flies emerge during August about the time that the martins return. In the laboratory diapause development was completed most rapidly at about 11 C. The parasites complete at least one nondiapausing generation during spring and early summer but diapausing puparaia begin to appear in the nests about the time of the summer solstice. It is not known whether the facultative diapause is induced by photoperiod or food.

Animals↗
PubMed1988

Migration of cultured fetal spinal cord astrocytes into adult host cervical cord and medulla following transplantation into thoracic spinal cord.

Cell suspensions from 14-day-gestation rat spinal cord, which had previously been soaked for 1 hr in a 2 micrograms/ml solution of Phaseolus vulgaris leucoagglutinin (PHAL), were cultured on collagen gels containing laminin for 2 weeks. Pieces of the gel and attached cells were then transplanted into the dorsal column of adult host thoracic spinal cord. At 1, 2, and 3 months postimplantation (MPI), animals were sacrificed, and the spinal cords were removed, embedded in paraffin, and sectioned at 8 micron for immunohistochemistry at the light microscopic level. Sections were double labeled for PHAL and utilized as a marker for transplant-derived cells and glial fibrillary acidic protein (GFAP), a specific marker for astrocytes. Transplant-derived astrocytes (PHAL-GFAP positive cells) migrated from the transplantation site in both rostral and caudal directions and were observed within the host dorsal column ipsilateral to the transplantation site. At 2 months, lateral migration into the contralateral dorsal column and ipsilateral dorsal horn was observed. At 3 MPI transplant-derived astrocytes were observed in host medulla (nucleus gracilis). Transplant-derived astrocytes were also observed on the glial limitans as far as nucleus gracilis. A migration rate of 0.72 mm/day was calculated, assuming a 14-day delay in the initiation of migration. The ramifications of such extensive migration are discussed with regard to return of function and amelioration of lesion-induced deficits.

Animals↗
PubMed1984

A 22-year study of paroxysmal trigeminal neuralgia in 211 patients with a 3-year appraisal of the role of cryotherapy.

The scope of this investigation included a comparative study of 211 patients with paroxysmal trigeminal neuralgia (PTN) seen over 22 years (from 1959 to 1981) and the use of an open-nerve freezing technique (cryotherapy) on peripheral branches of the trigeminal nerve in 42 of these patients over 3 years (from 1978 to 1981). The study was divided into three parts. Part I was an analysis of clinical findings in all patients. Part II dealt with 33 medically uncontrolled patients and was an assessment of cryotherapy under the most adverse conditions. Part III consisted of an unselected group of 16 patients whose pain could be controlled by chemotherapy but who were not in remission. It was an assessment of cryotherapy in 9 of them as a replacement or adjuvant to chemotherapy. A total of 62 operations were performed, resulting in immediate pain relief and the gradual return of sensation in the treated nerve in all patients. The procedure had to be repeated in 6 patients early in the study to achieve this; one probable reason was inadequate freezing. The longest period of relief has been 2 1/2 years so far; the first patient treated 3 years ago, failed to return and could not be traced. Migration of pain to smaller branches of the trigeminal nerve occurred in 16 patients from 3 to 9 months postoperatively. This was abolished by further cryotherapy in the areas of migration. It is postulated that cryotherapy acts both peripherally and centrally to produce pain relief; if the technique is correctly carried out, the results can be long lasting and may be permanent.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Alternating phases of FGF receptor and NGF receptor expression in the developing chicken nervous system.

Patterns of expression of transcripts encoding receptors for fibroblast growth factor and nerve growth factor (FGF-R and NGF-R) in the developing chick nervous system are compared using in situ hybridization histochemistry. FGF-R transcripts are expressed abundantly in the germinal neuroepithelial layer. Expression ceases as cells migrate into the mantle layer and returns during late maturation of neuronal populations, including cholinergic nuclei of the basal forebrain, brainstem reticular and motor nuclei, and cerebellar Purkinje and granule neurons. The pattern of NGF-R expression is generally reciprocal to that of FGF-R in the CNS and in some phases of development of the PNS. These results suggest that FGF and NGF may act sequentially rather than in concert during neuronal development.

Animals↗
PubMed1992

Maturing thymocytes in accelerated rejection of cardiac allografts in presensitized rats.

LBNF1 cardiac allografts are rejected within 36 hr in LEW rats sensitized with BN skin grafts 7 days earlier (acute rejection in unmodified hosts = 8 days). We have studied and compared the function and migration patterns of thymocytes one day after engraftment in sensitized recipients, unmodified hosts, and normal naive rats. Thymocytes from animals experiencing accelerated rejection were more mature and functionally active, as shown by a significant elevation in percentage of OX-44+ (CD37+) cells, increased alloreactivity to BN and WF antigens, and proliferative responses to Con A and exogenous IL-2. However, the cells could neither lyse BN targets in vitro nor trigger rejection of otherwise indefinitely functioning test cardiac allografts in immunologically unresponsive T cell-deficient (B) rats after adoptive transfer. The traffic of 111In-labeled thymocytes was then evaluated. The migration index increased significantly during accelerated graft rejection, with thymocytes preferentially circulating in the blood, penetrating peripheral lymph nodes--and, interestingly, migrating back to the thymus. Thus, immunoresponsive and functionally active thymocytes, which lack the ability to recognize primed specific antigen, appear during accelerated rejection of cardiac allografts in sensitized rats. These cells migrate to the periphery, and then return in large numbers to their site of origin, the thymus. Hence, this study describes a novel behavior of thymocytes in the state of host alloreactivity that is distinct from the physiological one in otherwise normal thymus.

Animals↗
PubMed1999

Tomato chlorotic dwarf viroid: an evolutionary link in the origin of pospiviroids.

Over 40 isolates of potato spindle tuber viroid (PSTVd) have been reported from potato, other Solanum species and greenhouse tomato. These isolates have sequence similarities in the range 95-99%. A viroid which caused chlorotic leaves and severe dwarfing of plants in greenhouse tomato crops was detected. The viroid was found to hybridize readily with PSTVd probes. It migrated faster than PSTVd in return-polyacrylamide gel electrophoresis and was not amplified in RT-PCR by a primer pair based on the lower strand of the central conserved region of PSTVd. Nucleotide sequencing of the viroid indicated that it is a circular RNA of 360 nt, with less than 90% sequence similarities with PSTVd isolates. The Variable domain (V) has less than 60% and the Terminal Right domain less than 90% sequence similarity, while the remainder of the molecule has greater than 97% similarity with PSTVd. Because of its less-than 90% sequence similarities, unique V domain, lack of seed-transmission and lack of cross-protection by PSTVd, the viroid from tomato is proposed to be a distinct viroid species (tomato chlorotic dwarf viroid; TCDVd) which also differs from two viroids infecting tomato in nature. TCDVd may be an evolutionary link in the development of crop viroids, with Mexican papita viroid as the ancestral viroid.

Base Sequence↗
PubMed1998

The educational attainment of immigrants: trends and implications.

"This paper uses the 1970, 1980, and 1990 U.S. Censuses to study trends in educational attainment of immigrants relative to natives. Immigrants have become relatively less highly educated, but have become more highly educated in an absolute sense. The effects of changes in relative educational attainment between immigrants and natives on earnings are studied. Educational differences are found to explain more than half the observed wage gap between the two groups. The paper also allows for non-linearities in returns to education. Sheepskin effects influence earnings in different ways for natives and immigrants. Differences in returns to pre- and post-migration education also appear. The paper also finds evidence that immigrants crowd natives out of education, although the effects are stronger in secondary than in postsecondary education."

Americas↗
PubMed1987

Gastroduodenal motility in neonates: response to human milk compared with cow's milk formula.

It is known that breast milk empties more quickly from the stomach than does infant formula. We studied the difference in gastroduodenal motility between neonates fed with human milk and those fed with infant formula. Twenty-four five- to 36-day-old neonates were fed with mother's breast milk or with a cow's milk-based formula. Postprandial gastroduodenal contractions were recorded manometrically for three hours. Repetitive, high-amplitude nonmigrating contractions were the dominant wave form during the postprandial period. The number of episodes, duration, amplitude, and frequency of nonmigrating contractions were not different following the different feedings. The migrating myoelectric complex, which signals a return to the interdigestive (fasting) state, appeared in 75% of breast milk-fed infants but only 17% of formula-fed infants (P less than .05) within the three-hour recording period. Because contractions were similar following the two meals, but a fasting state recurred more rapidly in breast-fed infants, we conclude that factors other than phasic, nonpropagated antroduodenal contractions were responsible for the differences in gastric emptying between breast milk and formula.

Adult↗