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Biomedical subjects

A Robertson

Publications and source records attributed to A Robertson.

At least 19 recordsLinked to original sources
PubMed1991

The route of lysine breakdown in Candida tropicalis.

Candida tropicalis was found to contain high levels of the following enzymes after growth in defined medium on L-lysine as sole nitrogen source: L-lysine N6-acetyltransferase, N6-acetyl-lysine aminotransferase, and aminotransferase activity for 5-aminovalerate and 4-aminobutyrate. Extracts were also capable of converting 5-acetamidovalerate (and 4-acetamidobutyrate) to acetate. N6-Acetyllysine however, only gave rise to acetate in the presence of 2-oxoglutarate, NAD+ and thiamine pyrophosphate. These activities were undetectable or present in much lower concentrations in cells that had been grown on ammonium sulphate as sole nitrogen source. It is concluded that L-lysine is degraded in this organism via N6-acetyllysine, 5-acetamidovalerate and 5-aminovalerate, both nitrogen atoms being removed by transamination.

Acetates↗
PubMed1991

Long-term treatment of ventricular tachycardia with amiodarone in presence of severe left ventricular dysfunction.

A group of 34 consecutive patients with coronary artery disease (n = 29) or dilated cardiomyopathy (n = 5) (3 women, 31 men, age 38-80 yr) who had severely impaired left ventricular function (left ventricular ejection fraction less than or equal to 40%) and high-grade ventricular ectopic activity (sustained or nonsustained ventricular tachycardia or ventricular fibrillation) were treated with amiodarone (mean dose: 206 mg/d) and followed for 1-117 (mean: 49) months. In the total group, there were seven sudden deaths, five deaths due to pump failure, one non-cardiac death, and two successful heart transplantations during follow-up. Thus the annual cardiac mortality in these carefully selected and followed patients was 8, 6%, the annual cardiac event rate was 10, 1%. The cumulative cardiac survival-rate was 62% after 5 years and 41% after 10 years. In five patients, treatment was interrupted after 10 to 43 months, three of the patients were alive at follow-up and two suffered cardiac death, resulting in an annual cardiac death rate of 12% in this subgroup of treatment. Based on the results of this retrospective analysis we conclude that in patients with low left ventricular ejection fraction and nonsustained or sustained ventricular tachycardia treated with low dose amiodarone, mortality was unexpectedly low. Thus, it may be the antiarrhythmic treatment to be considered in patients with ventricular tachycardia and severe left ventricular dysfunction.

Adult↗
PubMed1991

Sensory nerve pathology in amyotrophic lateral sclerosis.

A detailed morphometric study was performed on sural nerve biopsies to determine the consistency of sensory nerve pathology in amyotrophic lateral sclerosis (ALS) and to seek a correlation between the severity of peripheral nerve pathology and disease duration. Nerve biopsies from patients with ALS consistently showed evidence of early axonal atrophy, increased remyelination and a shift in the diameter distributions curve towards smaller fiber diameters. Importantly, the severity of sensory nerve pathology in ALS patients correlated with disease duration. The peripheral nerve sodium pump concentration of patients was not reduced. It is concluded that an ingravescent dorsal root ganglion neuronopathy is seen in the incipient stages of ALS, preferentially affecting the largest neurons and resulting in turn in progressive axonal atrophy, secondary demyelination-remyelination and finally in nerve fiber degeneration. Etiologically, a parallel involvement of motor and sensory neurons suggests a more widespread metabolic disturbance in ALS than simply "sick" motor neurons.

Adult↗
PubMed1991

Structure activity hypotheses in occupational asthma caused by low molecular weight substances.

Many substances with a low molecular weight (less than 1000 molecular weight) but of different chemical classes are recognized as causative agents of occupational asthma. Some of their major chemical properties are highlighted in relation to their putative interactions with human macromolecules. Thus, certain transition metals which form co-ordination complexes may chelate human proteins. Several organic substances have marked basic properties which are responsible for their chemical reactivity. Some of these, such as the bifunctional bases ethylene diamine, piperazine and para-phenylene diamine are known causative agents of asthma while their monofunctional counterparts, in spite of wide industrial application, are not similarly recognized causes. This suggests that the presence of multiple reactive groups is of importance in the molecular interactions with human macromolecules that eventually lead to occupational asthma. Reference is also made to other substances to exemplify hypothetical mechanisms of these interactions. Such generation of hypotheses is a prelude to quantitative studies of structure activity relationships (QSARs) where the hypotheses can be tested and revised. Structure activity hypotheses in isolation might not be adequate predictors of the risk of occupational asthma. However, if applied to novel chemical entities they might eventually prove useful in contributing to the development of policies for prospective health surveillance and in establishing priorities for epidemiological research.

Air Pollutants, Occupational↗
PubMed1991

Transabdominal chorion villus sampling: a safe and reliable procedure.

A complete follow-up of the first 578 patients undergoing transabdominal chorion villus sampling (TACVS) in our combined practices was undertaken to determine the pregnancy loss rate. Factors contributing to losses and the problems incurred in achieving a clinically relevant result were also examined. It was found that increasing experience led to fewer procedural difficulties but that there persisted a higher problem rate in those women with a retroverted uterus. In 98.1% of patients an adequate volume of tissue was obtained and in 95.5% a clinically relevant result was achieved. This second figure rose to 96.3% in the latter part of the study. There was a total fetal loss rate of 2%, with only 0.5% (3 patients) having a missed abortion within 4 weeks of the procedure. It is concluded that TACVS is a reliable procedure with a high level of safety.

Abdomen↗
PubMed1991

Effect of drug combinations on bilirubin-albumin binding.

Drugs which compete with bilirubin for albumin binding may increase the risk of kernicterus. Fortunately, few drugs are strong competitors. However, in neonatology, many drugs are used simultaneously. We have studied the effect of drug combinations on bilirubin binding using human serum albumin and the peroxidase method. Combinations of aminophylline with phenobarbital, cefotaxime and vancomycin were studied as well as the combination of vancomycin and cefotaxime. The results show that the bilirubin-displacing effect of the drug combinations cannot be predicted from each drug's individual effect. These results are consistent with a flexible model of albumin binding. Combinations of drugs which are both albumin-bound and reach high serum concentrations should be tested for their combined effect on bilirubin binding and this information used in deciding on treatment in sick, premature infants.

Aminophylline↗
PubMed1991

Generational equity and public health policy: a critique of "age/race war" thinking.

A potent new tool in the politics of fiscal retrenchment lies in the creation of a framework for policy analysis which implicitly or explicitly "blames" the old for poverty and economic hardships in the young. This paper examines the recent efforts to promulgate this generational equity or "age/race wars" perspective and demonstrates that opinion poll data fail to support the rhetoric of growing age/race group antagonisms over entitlement programs for the old. The assumptions underlying the generational equity framework are critiqued, and the race and ethnic issues embedded within this framework are examined. In particular, we explore spurious assumptions concerning the relative financial wellbeing of the elderly, escalating Social Security and Medicare costs as a primary cause of poverty in the young, and growing resentment of programs for the old among minorities and youth. Attempts to deligitimate the claims of the elderly through the advancement of the ideology of age/race wars are seen to have significant implications for public health policy, with the country's recent experience with the Medicare Catastrophic Coverage Act serving as an important case in point. The need for an alternative policy framework stressing the interdependence of generations is suggested, and some guiding principles put forward toward the development of such an alternative framework.

Age Factors↗
PubMed1990

Chromosome 6q deletions: a report of two additional cases and a review of the literature.

Here we report on two additional cases of distal 6q deletions with one case showing a terminal deletion of chromosome 6 (46,XY, del(6)(pter----q26:)) and one case showing an interstitial deletion of chromosome 6 (46,XY, del(6)(pter----q23::q25----qter)). The association of retinal abnormalities in 6q deletions is supported, and the additional manifestations of skin hyperextensibility, sacral abnormality, and imperforate anus are described.

Abnormalities, Multiple↗
PubMed1990

Comparison of the binding characteristics of serum albumins from various animal species.

In order to develop an animal model to study the bilirubin displacing effect of various drugs, we compared the bilirubin binding ability of human, pig, dog, rabbit, hamster, rat, guinea pig, and cat albumin. These albumins were used also to study the binding of monoacetyldiaminodiphenyl sulfone (MADDS). Using human, rat, guinea pig, and rabbit albumin, we studied the effect of sulfisoxazole, ceftriaxone, and tin protoporphyrin on bilirubin binding. Our results demonstrate that each animal albumin has different binding characteristics for the various chemicals tested. This variable must be considered before using an animal as a model for studying factors influencing bilirubin deposition in the brain.

Animals↗
PubMed1990

The politics of Alzheimer's disease: a case study in apocalyptic demography.

Catastrophic projections of the burden to society of an increasing aging population abound. The prevailing belief is that an increasing dependent aging population means increasing demands on the resources of society, including health care resources, in the face of competing interests and diminishing, or at best finite, resources. But how justified is this "apocalyptic demography"? This article presents one challenge to the apocalyptic scenario by considering the politics surrounding the most publicized, although not the most prevalent, disease of elders: Alzheimer's disease. The recent emergence of Alzheimer's disease as the "fourth or fifth leading cause of adult deaths" is critically examined, and the evidence for the social construction of Alzheimer's disease in terms of the "biomedicalization of aging" discussed. The author considers that it is, in part, the response of the health care system (as it is currently constituted) to changes in demography and disease distribution--and not, as is commonly asserted, the numbers of elders or their increasing "morbidity"--that drives up health care costs.

Aged↗
PubMed1989

Sick building syndrome.

Sick building syndrome is the recently coined phrase for the multitude of symptoms which office workers may suffer related to their working environment. Management involves a team approach between GPs, the occupational health service and the employer.

Environmental Exposure↗
PubMed1989

Mate choice on fallow deer leks.

Leks, on which males defend small clustered mating territories, may have evolved because of the unusual opportunities they provide for female choice of mating partners, and several studies of lek-breeding animals have demonstrated correlations between the mating success of males and their phenotype or behaviour. However, these could arise because (1) females select mates on the basis of male phenotypic traits; (2) males interfere with each other's mating attempts; or (3) females show preferences for particular mating territories, and larger or stronger males are more likely to win access to these territories. Here we report that when fallow bucks on a traditional lek were experimentally induced to change their territories, differences in the mating success of bucks persisted, whereas differences in the position of their territories relative to the centre of the lek did not. The observation that bucks rarely interfered with their neighbours' harems and females moved freely between bucks suggests that females choose their mates on the basis of male phenotype rather than territory type or location. In this population, the immediate factor affecting the movements of females between males was the size of a buck's harem.

Animals↗