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Biomedical subjects

J Hartley

Publications and source records attributed to J Hartley.

12 recordsLinked to original sources
PubMed1992

Prostacyclin production from seeded prosthetic vascular grafts.

Endothelial cell seeding has been proposed as a method of improving patency rates in small-calibre prosthetic vascular grafts. In vivo, endothelial cells normally produce prostacyclin (PGI2), a potent antiplatelet agent. The aim of this study was to determine whether seeded grafts show significant PGI2 production after in vivo implantation. Grafts were seeded with either autologous canine venous endothelial cells or autologous microvascular endothelial cells. After 12 weeks, PGI2 production was assessed under basal and stimulated conditions. Seeded grafts were compared with non-seeded controls and the corresponding aorta. The overall patency rate in seeded grafts was 80 per cent compared with 10 per cent in non-seeded grafts (P < 0.01). Grafts seeded with cells from either source produced significantly more PGI2 than unseeded grafts in both basal and stimulated states (P < 0.05). The aorta produced significantly more PGI2 than seeded grafts under both conditions (P < 0.01). Endothelial cell seeding produces a functional graft and leads to an improved patency rate.

Animals↗
PubMed1992

Maximum intra-thoracic pressure with anti-G straining maneuvers and positive pressure breathing during +Gz.

Positive pressure breathing during +Gz (PBG) and anti-G straining maneuvers (AGSM) each improve +Gz tolerance by increasing blood pressure through increases in intra-thoracic pressure, but the maximal intra-thoracic pressure from their combined effect is not known. Six subjects performed the following: 1) maximal AGSM at +1 Gz; 2) assisted PBG (constant 60 mm Hg) at +Gz; 3) submaximal AGSM at +Gz (enough to maintain peripheral vision); 4) maximal AGSM at +Gz; and 5) combined PBG and maximal AGSM at +Gz. They wore TLSS mask/helmet ensemble, CSU-15/P G-suit, and TLSS-style jerkin. Intra-thoracic pressure was measured with a catheter-tip pressure transducer in the esophagus (Pes). The change in gastric pressure was also measured (delta Pga). For both Pes and delta Pga, there were no significant differences among experimental conditions (1), (4) and (5), as above. Group mean Pes and delta Pga in these three conditions were 139 and 197 mm Hg, respectively. The similar results between maximal AGSM, and maximal AGSM and PBG are explained by limited support from the thoracic counter-pressure garment, and the characteristics of the respiratory system.

Blood Pressure↗
PubMed1987

Asbestos and cancer: a cohort followed up to death.

The mortality experience of 1074 white men who retired from a United States asbestos company during the period 1941-67 and who were exposed to asbestos working as production and maintenance employees for the company is reported to the end of 1980 when 88% of this cohort was known to be dead. As noted in earlier reports the mortality for respiratory and gastrointestinal cancer was raised. A more detailed examination of causes of death shows that the excess in gastrointestinal cancer was largely due to a statistically significant excess in stomach cancer. A statistically significant excess was also noted for kidney cancer, cancer of the eye, and non-malignant respiratory disease. Eight deaths from malignant mesothelioma were observed, two of which were peritoneal. Asbestos exposures for these mesothelioma cases were low relative to other members of the cohort. Continuing follow up of this cohort shows a dose response relation for respiratory cancer that has become increasingly linear. Standardised mortality ratios peaked 10 to 15 years after retirement and were relatively constant at around 250 in each five year interval starting in 1950. This excess might have been detected as early as 1960 but certainly by 1965. The mortality experience of this cohort reflects the ultimate effects of asbestos since nearly all of the cohort has now died.

Aged↗
PubMed1987

Acceleration of coronary collateral development by heparin in conscious dogs.

We evaluated whether heparin pretreatment accelerates the development of coronary collateral vessels induced by repeated, brief coronary occlusions. Sixteen dogs were instrumented for the measurement of subendocardial segment length in the area perfused by the left circumflex coronary artery (LCCA), LCCA flow and left ventricular pressure. An externally inflatable pneumatic occluder was placed around the LCCA. Two min coronary occlusions (CO) at rest were repeated hourly until there was no reduction in ischemic segment systolic shortening at the end of CO and negligible reactive hyperemia following the release of CO. Eight control dogs developed collaterals sufficient for resting myocardial oxygen requirements in the LCCA region by 129 +/- 45 (SD) CO. The remaining 8 dogs given heparin daily developed collaterals by 81 +/- 33 CO (p less than 0.05). Thus, in the presence of severe myocardial ischemia known to promote collateralization, heparin accelerated the development of coronary collaterals.

Animals↗
PubMed1986

Differential cytotoxicity and DNA-damaging effects produced in human cells of the Mer+ and Mer- phenotypes by a series of alkyltriazenylimidazoles.

A series of alkyltriazenylimidazoles have been investigated for their differential cytotoxicity towards the HT-29 (Mer+) and BE (Mer-) cell lines and for their ability to cause DNA strand breaks and cross-links. A monomethyltriazene, and some hydroxymethyltriazene derivatives capable of generating the monomethyltriazene in situ, were preferentially cytotoxic towards the BE cell line compared with the HT-29 cell line, with very close similarity in the differential toxicity to the analogous monochloroethyltriazene. In contrast, the dimethyl- and monoethyltriazenes in the series display reduced toxicity towards the BE cell line with little or no differential toxicity between BE and HT-29 cell lines. With another pair of human cell lines, the IMR-90 (Mer+) and VA-13 (Mer-) cells, the monomethyl- and monochloroethyltriazenes were again more cytotoxic to the Mer- cells. Neither the formation of DNA single-strand breaks or DNA-protein cross-links could account for the differential cytotoxicity observed in the Mer+ and Mer- cells. More importantly, the inability of the monofunctional monomethyltriazene to cross-link DNA tends to question the role of DNA inter-strand cross-linking as a mechanism for cell killing by chloroethylating agents.

Alkylation↗
PubMed1979

Factors affecting the growth and titration by immunofluorescence of simian foamy virus.

This paper presents some observations concerned with the growth of simian foamy virus and some modifications which should be introduced to the fluorescence assay of foamy virus. The modified procedure is the most sensitive method described for the titration of foamy virus. Examination of the optimal conditions for the growth and titration by fluorescence assay of simian foamy virus showed that the virus was particularly sensitive to changes in virus and cell concentration. At the low cell concentrations employed previously a "saturation-type" response was obtained with high titre virus and virus adsorption efficiency was decreased as input virus was diluted. Maximum virus production was obtained with high cell concentrations at input multiplicities of 5 and 10. At high multiplicities of infection more than 90 per cent of the cells adsorbed virus but only 45 per cent became infected, this appeared to be related to cell DNA synthesis.

Adsorption↗
PubMed1979

Comparison of the antigens produced by foamy virus in a cytolytic and a persistent infection of HEp2 cells.

The antigens from cytolytic infections of HEp2 cells by type I simian foamy virus produced two multicomponent precipitation lines when tested by immunodiffusion with the homologous hyperimmune rabbit antiserum. The antigens obtained from a non-productive infection of MK5 virus in HEp2 cells produced only those precipitation lines which corresponded with the inner lines obtained from the cytolytic infection. Similarly, hyperimmune rabbit antiserum against antigens extracted from the persistent infection lacked the antibody which was responsible for the outer lines of precipitation. Indirect immunofluorescence with acetone-fixed and unfixed cells using the homologous and heterologous sera confirmed the absence of antigens in the persistent infection and showed that an antigen is produced in the persistently infected cells which is either absent or present in very small amounts in cytolytically infected cells. Neutralization experiments and ether treatment suggested that the missing antigens in the persistent infection were the envelope components of foamy virus. It is proposed that the persistent infection has properties in common with some infections by RNA tumour viruses.

Antigens, Viral↗
PubMedDate not supplied

Lung cancer among women residing close to an arsenic emitting copper smelter.

Lung cancer deaths occurring between 1935 and 1969 among women residing near an arsenic emitting smelter were examined. For three geographically defined exposure groups, the observed and expected number of lung cancer deaths were compared. In none of the exposure groups did the observed number of deaths exceed the expected. However, an index of exposure based on distance of residence from the smelter and duration of residence in the area was 27% higher for cases than for age-matched controls (p = .10). Adjusting for a latency of 20 yr, case exposures were 23% higher than for controls (p = .07). Dividing individuals into quintiles of exposure yielded odds ratios ranging from 1 to 1.6 (test of trend, p = .07).

Adult↗
PubMedDate not supplied

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Health Facility Environment↗