Ecological immunization: in situ training of free-ranging predatory lizards reduces their vulnerability to invasive toxic prey.

In Australia, large native predators are fatally poisoned when they ingest invasive cane toads (Rhinella marina). As a result, the spread of cane toads has caused catastrophic population declines in these predators. Immediately prior to the arrival of toads at a floodplain in the Kimberley region, we induced conditioned taste aversion in free-ranging varanid lizards (Varanus panoptes), by offering them small cane toads. By the end of the 18-month study, only one of 31 untrained lizards had survived longer than 110 days, compared to more than half (nine of 16) of trained lizards; the maximum known survival of a trained lizard in the presence of toads was 482 days. In situ aversion training (releasing small toads in advance of the main invasion front) offers a logistically simple and feasible way to buffer the impact of invasive toads on apex predators.

3D optic disc reconstruction via a global fundus stereo algorithm.

This paper presents a novel method to recover 3D structure of the optic disc in the retina from two uncalibrated fundus images. Retinal images are commonly uncalibrated when acquired clinically, creating rectification challenges as well as significant radiometric and blur differences within the stereo pair. By exploiting structural peculiarities of the retina, we modified the Graph Cuts computational stereo method (one of current state-of-the-art methods) to yield a high quality algorithm for fundus stereo reconstruction. Extensive qualitative and quantitative experimental evaluation (where OCT scans are used as 3D ground truth) on our and publicly available datasets shows the superiority of the proposed method in comparison to other alternatives.

Prediction of peak oxygen uptake in chronic fatigue syndrome.

OBJECTIVES: To establish a simple, valid, and acceptable method of predicting peak oxygen uptake (VO2peak) in patients with chronic fatigue syndrome (CFS), which could provide a basis for subsequent exercise prescription at an appropriate intensity as part of a clinical rehabilitation programme. METHODS: A total of 130 patients who met UK research criteria for CFS were taken from consecutive referrals for chronic fatigue to the University Department of Medicine at Withington Hospital, Manchester. VO2peak was determined using an incremental graded exercise test to exhaustion. Respiratory gas exchange, work rate, and heart rate were monitored throughout. RESULTS: In all patients, VO2peak was found to correlate strongly and significantly with peak work rate (WRpeak) during testing (r2 = 0.88, p<0.001). In patients who exercised for longer than two minutes (n = 119), regression analysis established the relation as Vo2peak = 13.1 x WRPpeak + 284, where VO2 is given in ml/min and WR in W. The mean error between the measured VO2peak and the predicted value was 10.7%. The relation between increase in work rate and oxygen uptake across the group was highly significant (r2 = 0.87, p<0.001), and given as VO2increase = 12.0 x WRincrease, this value being similar to that expected for healthy individuals. Almost all (97%) subjects reported no exacerbation of symptoms after maximal exercise testing. CONCLUSIONS: Using a simple to administer maximal exercise test on a cycle ergometer, it is possible to predict accurately the VO2peak of a patient with CFS from peak work rate alone. This value can then be used as an aid to setting appropriate exercise intensity for a rehabilitation programme. The increase in VO2 per unit increase in workload was consistent with that expected in healthy individuals, suggesting that the physiological response of the patients measured here was not abnormal. Contrary to the belief of many patients, maximal exercise testing to the point of subjective exhaustion proved to be harmless, with no subjects suffering any lasting deterioration in their condition after assessment.

Randomised, double-blind, placebo-controlled treatment trial of fluoxetine and graded exercise for chronic fatigue syndrome.

BACKGROUND: The Joint Working Group of the Royal Colleges of Physicians, Psychiatrists and General Practitioners (1996) recommended graded exercise and antidepressants for patients with chronic fatigue syndrome. We assessed efficacy and acceptability of these treatments. METHOD: Six-month prospective randomised placebo and therapist contact time controlled trial with allocation to one of four treatment cells: exercise and 20 mg fluoxetine, exercise and placebo drug, appointments only and 20 mg fluoxetine, appointments and placebo drug. Drug treatment was double blind and patients were blind to assignment to exercise or appointments. RESULTS: Ninety-six (71%) of 136 patients completed the trial. Patients were more likely to drop out of exercise than non-exercise treatment (P = 0.05). In an intention to treat analysis, exercise resulted in fewer patients with case level fatigue than appointments only at 26 weeks (12 (18%) v. 4 (6%) respectively P = 0.025) and improvement in functional work capacity at 12 (P = 0.005) and 26 weeks (P = 0.03). Fluoxetine had a significant effect on depression at week 12 only (P = 0.04). Exercise significantly improved health perception (P = 0.012) and fatigue (P = 0.028) at 28 weeks. CONCLUSIONS: Graded exercise produced improvements in functional work capacity and fatigue, while fluoxetine improved depression only.

Chromosomal rearrangements in rock wallabies, Petrogale (Marsupialia: Macropodidae). IX. Further G-banding studies of the Petrogale lateralis complex: P. lateralis pearsoni, the west Kimberley race, and a population heterozygous for a centric fusion.

G-banded metaphase preparations from cultured fibroblasts were used to examine the karyotypes of Petrogale lateralis pearsoni and the West Kimberley (WK) race of P. lateralis. Petrogale lateralis pearsoni was found to retain the ancestral 2n = 22 Petrogale karyotype, while the WK race (2n = 20) was found to be characterized by a 9-10 centric fusion. This taxon had been reported to have an 8-10 fusion. Karyotypic analysis was also used to identify Petrogale populations in the Erskine Range, Western Australia (W.A.) as the WK race and in the Walter James Range, W.A. as the MacDonnell Ranges (MDR) race of P. lateralis. These findings represent significant range extensions for both taxa. A third P. lateralis population, from the Townsend Ridges, W.A., could not be definitively identified to subspecies or race and appears intermediate between the WK and MDR races. Four animals were examined from this population and all possessed an identical 2n = 21 karyotype characterized by homozygosity for a derived acrocentric chromosome 3 (3a) and heterozygosity for a 9-10 fusion. Rearrangement 3a is typical of the MDR race, while the 9-10 fusion is characteristic of the WK race. The polymorphic Townsend Ridges population could result from the de novo creation of a 9-10 fusion (similar in morphology to the 9-10 fusion of the WK race) or it may represent evidence of hybridization between the MDR race and either the WK race or a currently unknown taxon. Additional data will be required to distinguish between these hypotheses.

Plasma, platelet and erythrocyte glutathione peroxidases as risk factors in ischaemic heart disease in man.

1. Plasma, platelet and erythrocyte glutathione peroxidase activities and serum lipid concentrations were measured in patients with ischaemic heart disease and matched control subjects. 2. Mean plasma and platelet glutathione peroxidase activities were significantly lower in the patients with ischaemic heart disease. Erythrocyte glutathione peroxidase activities and serum lipid concentrations were similar in patients with ischaemic heart disease and control subjects. 3. No correlations between plasma, platelet and erythrocyte glutathione peroxidase activities were observed. 4. The combination of plasma and platelet glutathione peroxidase activities provided an 86% discrimination between patients with ischaemic heart disease and matched control subjects. 5. Our data suggest that plasma and platelet glutathione peroxidases may be significant risk factors for ischaemic heart disease. Plasma glutathione peroxidase is a previously unrecognized risk factor.

Proline transport by tsetse fly Glossina morsitans flight muscle mitochondria.

1. Proline accumulation by tsetse fly Glossina morsitans flight muscle mitochondria was studied in vitro by the swelling technique and direct measurement of (U-14C) proline. 2. Proline transport was inhibited by the uncharged liposoluble -SH reagent, N-ethylmaleimide but not by ionic reagent, mersalyl, suggesting that the -SH groups involved in the transport of proline are located in a hydrophobic part of the membrane or on the matrix side of the membrane. 3. The kinetic study of proline accumulation revealed saturation kinetics and a high temperature dependence. It gave a Km of 85 microM and a Vmax of 962 pmol/min/mg protein and an activation energy (Ea) of 11 kcal/mol. 4. Certain other amino acids (L-valine, L-alanine, L-methionine, L-phenylalanine, L-tryptophan and L-hydroxyproline) significantly stimulated proline uptake. 5. These observations indicate that tsetse fly Glossina morsitans flight muscle mitochondria contain a proline transport mechanism.

Pseudo-food allergy.

This article covers the background and general concepts pertaining to pseudo-allergy, the problems involved in reaching valid diagnoses of food allergy, the basics of the methodology of double-blind oral provocation, and the emotional, psychologic and recent sociologic factors particularly relevant to the inappropriate attribution of symptoms to allergy.

Selenium status in relation to reduced glutathione peroxidase activity in aspirin-sensitive asthma.

Selenium status and its relationship to lowered platelet glutathione peroxidase activity was investigated in 18 subjects with aspirin (ASA)-induced asthma and in asthmatic and non-asthmatic ASA-tolerant subjects. Mean serum selenium concentration in ASA-tolerant asthmatics (1.25 microns/l; 98.5 micrograms/l) was significantly higher than that in ASA-induced asthma subjects (1.14 microns/l; 89.7 micrograms/l) and than that in healthy controls (1.15 microns/l; 91 micrograms/l). Although there was a correlation between serum selenium concentration and platelet glutathione peroxidase activity, enzyme activity was significantly lower in the ASA-induced asthma group compared to other groups even after correcting for selenium status. These results indicate that lowered platelet glutathione peroxidase activity in ASA-induced asthma is a product of both selenium availability and an unidentified syndrome-specific (possibly genetic) factor.

Human selenium status and glutathione peroxidase activity in north-west England.

Nutritional selenium deficiency disease, due to low soil selenium content, is well recognized in British livestock. The adequacy of the selenium status of 25 healthy human volunteers, 50 blood donors, 94 general medical patients and 106 allergy clinic patients was investigated in 1987/8 by measuring serum selenium concentration and platelet glutathione peroxidase activity. Mean serum selenium concentration for the entire study population was 92 micrograms/l. Significant linear correlations between serum selenium concentration and peroxidase activity indicate that a substantial proportion of both healthy volunteers and medical patients are of low selenium nutritional status. Twenty-five per cent of healthy volunteers and 50 per cent of medical patients had serum selenium values below those required for full expression of selenium-dependent enzyme activity. Deficiency of the antioxidant activities of selenium and selenium-dependent enzymes may be relevant to geographical differences in morbidity from a wide range of human disease states.

Abnormal platelet hydrogen peroxide metabolism in aspirin hypersensitivity.

The generation and degradation of hydrogen peroxide (H2O2) by platelets was investigated in aspirin hypersensitive and tolerant allergic subjects, and compared to that in general medical patients and healthy controls. H2O2 generation following triggering with anti-IgE, specific allergen, and with aspirin (ASA) and indomethacin was examined using a chemiluminescence assay. Platelet levels of the main intracellular enzyme responsible for H2O2 metabolism--glutathione peroxidase--were measured by a quantitative functional assay. H2O2 secretion could be triggered by anti-IgE in platelets from 15/29 ASA-tolerant atopics, and by relevant allergen in platelets passively sensitized with allergen-specific IgE. A similar response was observed following triggering with ASA, and with indomethacin, in platelets from 8/25 ASA-sensitive subjects. Mean platelet glutathione peroxidase activity was significantly lower in subjects with ASA-induced asthma, but not in subjects with non-asthmatic reactions to ASA, compared to all other groups. Within the ASA-sensitive group there was no correlation between low peroxidase activity and ASA-triggered chemiluminescence. Our findings emphasize the heterogeneity of ASA-intolerance syndromes and point to abnormal oxygen/peroxide metabolism as a common pathway underlying ASA-induced asthma.

Psychologic and somatic interrelationships in allergy and pseudoallergy.

A wide range of mental, behavioral, and nonspecific subjective somatic symptoms can be observed commonly in the course of the classic allergic diseases of the atopic syndrome (asthma, rhinitis, eczema, etc). These symptoms do not necessarily imply the presence of psychiatric disorder, nor do they indicate that allergic processes have a direct effect on cerebral function. These changes are the indirect result of the allergy and are usually secondary to extracerebral physical dysfunctions. The potential importance of the cerebral effects of hypoxemia in asthma, and of the central nervous system side effects of antiallergy medication, has received inadequate attention and requires more research. Failure to recognize the true significance of such valid clinical observations, combined with failure to recognize the importance of the use of techniques to overcome the effects of the placebo, suggestion, and observer bias have led to several misconceptions concerning the role of foods and inhalants in psychiatric and somatic syndromes unassociated with atopy. It is apparent that publicity directed to such views, and the use of unorthodox or unproven "allergy" procedures, can cause significant harm.

Cytoplasmic NADP-linked dehydrogenase activities in avian tissues.

Cytoplasmic activities of NADP-linked malic enzyme (E.C. 1.1.1.40), glucose-6-phosphate dehydrogenase (E.C. 1.1.1.49) and NADP-linked isocitrate dehydrogenase (E.C. 1.1.1.42) were determined in tissues of selected avian species, and compared with those in mammals. Malic enzyme was generally more active in avian liver and kidney than in the corresponding mammalian tissues. Hepatic activities as high as 200 units/g wet wt and 100 units/g wet wt were recorded in the Nectariniidae and the Ploceidae respectively. Glucose-6-phosphate dehydrogenase was generally less active in avian tissues than malic enzyme. In passerine birds activities were very low indeed, and in most cases spectrophotometrically undetectable. Malic enzyme and glucose-6-phosphate dehydrogenase were highly active in the adipose tissue of mammals but were inactive in the adipose tissue of birds. Marked increases in hepatic malic enzyme and glucose-6-phosphate dehydrogenase activities were associated in birds with premigratory fattening. Activities of isocitrate dehydrogenase were comparable in the corresponding avian and mammalian tissues, including adipose tissue.