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Biomedical subjects

J F Watkins

Publications and source records attributed to J F Watkins.

15 recordsLinked to original sources
PubMed1991

Ultrasonic angioplasty in totally occluded peripheral arteries. Initial clinical, histological, and angiographic results.

BACKGROUND: Ultrasonic angioplasty was recently shown to ablate thrombi and atherosclerotic plaques in vitro and to recanalize occluded arteries in experimental animal models. The goal of the present study was to examine the clinical feasibility of ultrasonic angioplasty. METHODS AND RESULTS: Intraoperative ultrasonic angioplasty was performed in vivo on totally occluded peripheral arteries (n = 7). The ultrasonic angioplasty device consists of a 1.6-mm diameter flexible wire attached to a piezoelectric crystal generating ultrasound at 20 kHz. The controls, totally occluded human atherosclerotic femoral arterial segments (n = 6), were crossed mechanically with the ultrasound wire ex vivo but without application of ultrasonic energy. Ultrasonic angioplasty achieved successful recanalization without perforation in all vessels. Angiograms of the treated arteries showed an average lumen patency of 82.5%. Histological examination of the recanalized arteries revealed that the recanalization had taken place through intima diffusely involved with complicated plaque. The treated arteries, compared with the controls, had greater area of recanalized lumen (5.9 +/- 1.8 versus 1.7 +/- 0.4 mm2, p less than 0.05) and more flow (49.3 +/- 16.0 versus 11.8 +/- 4.9 ml/min, p less than 0.03). The damage in treated and control arteries was similar. Size-distribution analysis of the plaque debris from the treated arteries showed that 41 +/- 5% of the debris was 0.2-8 microns, 48 +/- 8% was 8-30 microns, and the remainder was 30-100 microns. In the mechanically crossed arteries, there was a shift in the distribution to larger size debris with 47 +/- 1% greater than 100 microns (p less than 0.001). CONCLUSIONS: Ultrasonic angioplasty may be a useful clinical method for recanalization of total occlusions in patients with peripheral vascular disease. Ultrasonic energy appears to cause controlled injury to the atherosclerotic intima by selectively disrupting the ultrasound-sensitive occlusion.

Aged↗
PubMed1990

Interregional elderly migration and population redistribution in four industrialized countries. A comparative analysis.

Though differing in cultures, languages, and socioeconomic attributes, the industrialized nations of the world share a common characteristic: relatively low fertility levels and relatively high proportions of elderly people. These elderly persons are not spread uniformly across their national territories; they exhibit distinct population geographies. This article examines the elderly migration and population redistribution process in four industrialized countries, identifies their principal retirement regions, and analyzes the sources of regional elderly population growth in these regions. It concludes that the United Kingdom and the United States are approaching the final stages of their "elderly mobility transition," whereas Japan is only entering the first stage, with Italy occupying a position somewhere in between.

Aged↗
PubMed1990

Appalachian elderly migration: patterns and implications.

This article seeks to explore the patterns of population aging and elderly migration in Appalachia, with a focus on two distinct and different subregions: eastern Kentucky and western North Carolina. Although the framework of the study is demographic, the foundation is more related to overarching concerns of the implications of migration, particularly with respect to local economies and services, and the potential use of elderly migration as a development strategy.

Aged↗
PubMed1989

Gender and race differentials in elderly migration.

A number of studies have provided evidence that elderly migration in the United States is strongly selective in terms of the characteristics of the migrants. Such characteristics as age, gender, and race are commonly used in examinations of migrant selectivity, but the differences in spatial behavior of these subpopulations are still poorly understood. This article uses state-to-state migration data, categorized by age, gender, and race, to explore the comparative patterns of origins, destinations, and migration propensities, with a focus on the southeastern states of the country.

Aged↗
PubMed1988

Excision repair of UV damage in human fibroblasts reversibly permeabilized by lysolecithin.

We have examined nucleotide excision repair synthesis in confluent human diploid fibroblasts permeabilized with lysolecithin. Following a UV dose of 12 J/m2, maximal incorporation of [alpha 35S]dNTPs occurred at a lysolecithin concentration (approximately 80 micrograms/ml) where slightly more than 90% of the cells were initially permeable to trypan blue. However, autoradiography of cells, permeabilized at this lysolecithin concentration, demonstrated that only about 20% of the total cell population incorporated significant levels of 35S into DNA. This result presumably reflected the fact that approximately 20% of the total cell population remained permeable for much longer periods of time (up to 2 h) than the remaining cell population (less than 20 min). The incorporation of dNTPs by UV-irradiated, permeabilized cells appeared to be bona fide excision repair synthesis since: (1) Incorporation was completely absent in unirradiated, permeabilized cells and in irradiated, permeabilized repair-deficient cells. (2) Nucleotides incorporated in the presence of BrdUTP were associated with normal density DNA. (3) The apparent Km for all 4 dNTPs was 50-100 nM, in agreement with past reports on human fibroblasts irreversibly permeabilized by cell lysis. (4) DNA associated with the newly incorporated dNTPs underwent ligation and rearrangements in chromatin structure analogous to what is observed in intact human cells. Repair incorporation of dNTPs was rapid and linear during the first 2 h after UV irradiation and permeabilization. After this time, incorporation ceased or continued at a much slower rate. Cell viability experiments and autoradiography demonstrated that the cells permeabilized to [3H]dNTPs were capable of carrying out DNA replication and cell division. Thus, confluent human diploid fibroblasts can be reversibly permeabilized to labeled dNTPs by lysolecithin for the study of excision repair following physiologic doses of UV radiation. However, under these conditions, only a fraction of the cells remain permeable for an extended period of time.

Cell Membrane Permeability↗
PubMed1978

Tumour-necrosis factor from the rabbit. I. Mode of action, specificity and physicochemical properties.

Sera from rabbits injected with BCG and then with endotoxin contain a factor (tumour-necrosis factor TNF) which, even at high dilutions, is cytotoxic in vitro for mouse L cells and some other cell lines. Using a 51Cr-release assay, cytotoxicity was detected as early as 7-8 h after addition of TNF serum to L cells and cell death was evident microscopically by 24 h. TNF was cytotoxic at 37 degrees C but not at 21 degrees C or 4 degrees C, and acted on both dividing and non-dividing cells. The antimetabolites sodium azide and dinitrophenol partially protected L cells from TNF, suggesting that actively metabolizing cells are the most sensitive. Treatment of L cells with trypsin did not delay cytotoxicity nor was cytotoxicity inhibited in the presence of various saccharide derivatives of cell-surface glycoproteins. Rabbit TNF was remarkably stable with a mol. wt. of 40-50,000. It was eluted with the more acidic serum proteins on ion-exchange chromatography, but precipitated in 50%-saturated ammonium sulphate. Sensitivity to TNF could not be correlated with tumourigenicity of several animal and human lines tested nor with the production of C-type viruses.

Animals↗
PubMed1977

Properties of a cell line from human adenocarcinoma of the rectum.

A new, highly differentiated line of cells derived from adenocarcinoma of the rectum (HT55) is described. This line is noteworthy for the following features: 1. The role played in its development by the use of UV-inactivated Sendai virus to attach tumour cell clumps to plastic bottles. 2. Evidence that it produces RNA-containing material of density 1-5--1-16 g/ml. 3. Induction of bone formation in the stroma when grown in athymic mice. 4. Stimulation of primary CBA mouse embryo fibroblasts to form a transient nodule when mixed with them and injected into adult CBA mice. The karyotype and growth-cycle characteristics of the line are described.

Adenocarcinoma↗
PubMedDate not supplied

Photochemotherapy in human heart transplant recipients at high risk for fatal rejection.

Heart transplant recipients in whom high levels of lymphocytotoxic antibodies directed towards a spectrum of histocompatibility antigens develop frequently represent difficult management problems. Recipients of multiple transplants and multiparous females generally form higher levels of panel reactive antibodies, which have been associated with fatal rejection episodes and accelerated graft atherosclerosis. In this study, two multiple transplant patients with preexistent high levels of panel reactive antibodies and two multiparous women who were considered at risk of sensitization were treated with a new form of immunotherapy termed photochemotherapy in addition to conventional immunosuppression. High levels of panel reactive antibodies have been reduced, and patients have suffered few rejection episodes and no infectious complications. This preliminary experience shows that the addition of photochemotherapy to conventional regimens may improve the clinical course of hypersensitized transplant patients without additional immunosuppressive risk.

Adult↗
PubMedDate not supplied

Persistence of the Fc cytophilic antibody receptor in macrophage hybrid cells.

Hybrid cell clones were obtained from mouse macrophase/Ehrlich ascites cell fusions which showed the 'Fc' cytophilic antibody receptor site, phagocytosis and motility typical of macrophages. With continued growth of the clones for 11 weeks, the receptor became undetectable but could be unmasked by dilute trypsin treatment; subsequent remasking of the receptor could be prevented with cycloheximide treatment of the hybrid cells. These hybrids produced cystic anaplastic tumours in neonatal irradiated mice. Chinese hamster/mouse interspecific macrophage hybrid cells did not show macrophage markers. This was probably due to rapid loss of macrophage chromosomes from the hybrid cells.

Animals↗