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Biomedical subjects

J Dillon

Publications and source records attributed to J Dillon.

At least 91 records · Page 5Linked to original sources
PubMed1988

Characteristics and outcome of patients in whom reperfusion with intravenous tissue-type plasminogen activator fails: results of the Thrombolysis and Angioplasty in Myocardial Infarction (TAMI) I trial.

To examine the outcome of patients with persistent coronary artery occlusion despite treatment with intravenous tissue-type plasminogen activator (t-PA), the clinical course of 96 patients with persistent occlusion after 90 min of therapy was evaluated. All patients underwent cardiac catheterization 90 min after initiation of intravenous t-PA. Immediate coronary angioplasty (PTCA) was attempted when the infarct-related artery failed to reperfuse unless the vessel was technically unsuitable or the infarct was thought to be small. No baseline differences could be found between these 96 patients and 288 patients who achieved perfusion with the same protocol. Although patients with and without successful perfusion after t-PA had similar clinical courses before cardiac catheterization, those without perfusion had more complications (ventricular fibrillation, severe bradycardia, hypotension) during catheterization. PTCA achieved reperfusion with less than 50% residual stenosis in 73% of the 86 patients in whom it was attempted, while 16% were left with a high-grade (greater than 50%) residual stenosis and PTCA failed in 11%. Mortality was highest in the nine patients with complete PTCA failure (44%), compared with a 6% mortality in the 63 patients with an insignificant residual stenosis after PTCA and a 14% mortality in the 14 patients with reperfusion, but a greater than 50% residual stenosis after PTCA. In 10 patients with small infarcts (six), unsuitable anatomy (two), or "spontaneous" drug induced (but later) opening before contemplated PTCA (two), PTCA was not attempted and no mortality occurred. The in-hospital reocclusion rate after successful PTCA was 29%, despite the use of heparin and antiplatelet agents.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon↗
PubMed1988

Age-dependent effect of UV light in abnormal alpha neoprotein formation in the lens.

The aim of this study was to determine whether or not alpha neoprotein formation can occur in the lens in response to a photolytic process. Alpha crystallin from young calf and aged bovine lenses was irradiated for up to 22 hours with UV light. After cortical alpha crystallin had been irradiated, it completely preserved its quaternary antigenic determinants. In contrast, 24.3% of the bovine nuclear alpha crystallin completely lost their quaternary determinants as a result of irradiation. The latter population of molecules still preserved the association of A chains with B chains, suggesting the formation of abnormal proteins. The exposure to UV irradiation can cause the formation of alpha neoproteins from aged but not from young alpha crystallin. Comparison of photolytic rates based on spectroscopic and chromatographic parameters also show an age-related increase in the susceptibility of alpha crystallin to photolyze. It is suggested that this increase is due to the age-related formation of a photosensitizer in alpha crystallin.

Aging↗
PubMed1985

The photolysis of lens fiber membranes.

Calf lens fiber membranes were photolyzed in the presence and absence of sensitizers and scavengers. Photolytic damage was assessed by SDS-polyacrylamide gel electrophoresis, UV and fluorescence spectra and amino acid analyses. With irradiation, there is an apparent polymerization of the major membrane polypeptide (MP26) and the formation of material which does not enter SDS-polyacrylamide gels. Some degradation was also observed. These changes are accompanied by losses of histidine and tryptophan and changes in the UV spectra. The rate of photolysis is enhanced in the presence of the glucoside of 3-hydroxykynurenine (3-OH-KYN), a compound endogenous to the lens. The reaction is retarded in the presence of sulfhydryl-containing compounds such as glutathione.

Amino Acids↗
PubMed1985

The photosensitized oxidation of the calf lens main intrinsic protein (MP26) with hematoporphyrin.

Hematoporphyrin (HP), a drug used for the treatment of tumors including intraocular tumors, is an efficient photosensitizer. In addition to its therapeutic value, it also produces a phototoxic side effect in the skin. To test whether such effects may also occur in the eye, calf lens fiber membranes were photolyzed in the presence and absence of 1 mM HP. A marked increase (ca 5 times) in the photopolymerization of the calf lens membrane main intrinsic protein (MP26) was found in the presence of HP. Tenfold increases in destruction rates were found in losses of histidine. The MP26 was also photolyzed after tryptic and chymotryptic digestion to MP21, this resulted in an increased photopolymerization in the presence of 1 mM HP. These data suggest an age related increase in sensitivity of the lens fiber membrane proteins to such photoprocesses. The addition of both azide and penicillamine reduces the photosensitized loss of the main intrinsic protein.

Animals↗
PubMed1984

The endopeptidase-resistant protein fraction from human cataractous lenses.

With aging and cataract formation, modifications in absorption and fluorescence of the human lens proteins are observed. These changes have been investigated by the examination of the endopeptidase-resistant fraction isolated from human cataractous lenses. This fraction is highly enriched in atypical fluorescence and absorption (i.e. not attributable to tryptophan, tyrosine or phenylalanine). It has a molecular weight of approximately 3000, is enriched in acidic amino acids and has only a 280 nm shoulder in its u.v. spectrum. The material does not contain detectable levels of malondialdehyde or N-formylkynurenine. Upon acid hydrolysis the fluorescence and u.v. spectra remain unchanged with only a minor degree of cleavage observed. Structural studies on some of the cleavage products indicated the presence of oxindolyl alanine and kynurenine. These compounds could result from photo-oxidation of tryptophan.

Amino Acids↗
PubMed1984

Nondisulfide polymerization of gamma- and beta-crystallins in the human lens.

The water-soluble 43,000-dalton fraction (WS43) of the human lens has been shown to be heterogeneous. It appears to contain, in addition to actin, components related to the crystallins. Immunoblot reactions indicate that this polypeptide fraction is composed of dimers containing beta- and gamma-crystallin components. It has been estimated that 10-30% of this fraction arises by dimerization of gamma-crystallin. A possible route for the formation of the 43,000-dalton fraction is suggested by the observation that photolysis of gamma-crystallin with light greater than 295 nm leads to polymer formation, including the 43,000-dalton fraction. The polymerization products react with anti-WS43. The results suggest that photochemical reactions may lead to the accumulation of polymers of some of the crystallins with aging of the human lens. Similar covalently linked polypeptides have previously been shown to be present in the high molecular weight aggregates associated with cataract formation.

Aging↗
PubMed1984

Photolytic changes in lens proteins.

Many of the age related and cataractous changes that occur in the human lens may be due to some photolytic process. These include either the direct photolysis of lens protein or photosensitized reactions involving 3-OH Kyn glucoside. The extent to which these photochemical reactions play a role is determined by the level of lens oxygen and the presence of quenchers endogenous to the lens.

Adolescent↗
PubMed1983

The state of neutral lipids in normal and cataractous human lenses.

A simple and rapid high pressure liquid chromatographic method (HPLC) was developed to analyse the neutral lipid fraction from normal and cataractous human lenses. No differences were found between old normal and cataractous lenses suggesting that membrane deterioration in cataracts is not due to oxidation of these components. Several new lens components were isolated and identified including cholesterol metabolites, and vitamin E (alpha-tocopherol).

Adult↗
PubMed1981

The role of ergonomics in the development of performance tests for furniture.

The development of realistic performance tests for furniture has been the subject of a continuing research programme. Such tests are necessary to ensure that furniture is both durable and safe to use: This paper discusses the general philosophy that tests should be based on the actual use to which furniture is likely to be subjected. The forces which act on a piece of furniture may be conveniently divided into two categories - functional and non-functional. The former occurs when the activity is one for which the furniture was designed, while non-functional use covers misuse for which the furniture was not specifically intended but which inevitably occurs and which must be considered in its design. The success of performance tests depends largely on the reproduction of service loads and ergonomics has played an important role in the recording and measuring of human behaviour in relation to different types of furniture. This has led to the development of test rigs to reproduce loads occurring in practice. A number of examples are discussed. The comparison of results obtained from these tests with the performance of furniture in everyday use has shown that the tests do adequately reproduce the type of failure which is likely to occur in practice.

Journal Article↗
PubMed1979

Mid systolic notching of the pulmonary valve in the absence of pulmonary hypertension.

In a patient with idiopathic dilatation of the pulmonary artery the pulmonary valve echogram showed a prominent mid systolic closing motion or notching indistinguishable from that seen in pulmonary hypertension. Normal right ventricular and pulmonary arterial pressures were recorded simultaneously with echocardiograms of the pulmonary valve.

Adult↗