Phospholipid oxidation and carotenoid supplementation in Alzheimer's disease patients.

Alzheimer's disease (AD) is a progressive, neurodegenerative disease, characterised by decline of memory, cognitive function and changes in behaviour. Generic markers of lipid peroxidation are increased in AD and reactive oxygen species have been suggested to be involved in the aetiology of cognitive decline. Carotenoids are depleted in AD serum, therefore we have compared serum lipid oxidation between AD and age-matched control subjects before and after carotenoid supplementation. The novel oxidised phospholipid biomarker 1-palmitoyl-2-(5'-oxo-valeroyl)-sn-glycero-3-phosphocholine (POVPC) was analysed using electrospray ionisation tandem mass spectrometry (MS) with multiple reaction monitoring (MRM), 8-isoprostane (IsoP) was measured by ELISA and ferric reducing antioxidant potential (FRAP) was measured by a colorimetric assay. AD patients (n=21) and healthy age-matched control subjects (n=16) were supplemented with either Macushield™ (10mg meso-zeaxanthin, 10mg lutein, 2mg zeaxanthin) or placebo (sunflower oil) for six months. The MRM-MS method determined serum POVPC sensitively (from 10µl serum) and reproducibly (CV=7.9%). At baseline, AD subjects had higher serum POVPC compared to age-matched controls, (p=0.017) and cognitive function was correlated inversely with POVPC (r=-0.37; p=0.04). After six months of carotenoid intervention, serum POVPC was not different in AD patients compared to healthy controls. However, POVPC was significantly higher in control subjects after six months of carotenoid intervention compared to their baseline (p=0.03). Serum IsoP concentration was unrelated to disease or supplementation. Serum FRAP was significantly lower in AD than healthy controls but was unchanged by carotenoid intervention (p=0.003). In conclusion, serum POVPC is higher in AD patients compared to control subjects, is not reduced by carotenoid supplementation and correlates with cognitive function.

Severe cardiac failure associated with presumed jellyfish sting. Irukandji syndrome?

We present a retrospective review of twelve cases of Irukandji syndrome associated with pulmonary oedema. This is a life-threatening envenoming due to a presumed jellyfish sting throughout Northern Australia, although only one case occurred outside North Queensland. Patients presented with significant and ongoing pain, tachycardia and hypertension. Half the patients became hypotensive requiring inotropic support. Cardiac echocardiography revealed significant cardiac dysfunction. Six patients required ventilatory support. There was no death reported due to pulmonary oedema, but one patient died of intracerebral haemorrhage. We believe patients may develop a toxin associated cardiomyopathy, and jellyfish other than Carukia barnesi may be responsible. As there is confusion with nomenclature, Carukia barnesi should be known as the Barnes jellyfish, and the diagnosis of cardiotoxic marine envenoming is suggested for any patient who has been stung by a jellyfish, develops no or minimal skin markings, and develops cardiogenic pulmonary oedema associated with Irukandji syndrome.

Life-threatening cardiac failure in a healthy young female with Irukandji syndrome.

We present a case of a previously well 24-year-old female patient who developed severe and life-threatening Irukandji syndrome that required ventilation and inotropic support. This case provides further evidence that there are jellyfish other than the Irukandji jellyfish that can cause cardiac decompensation, and there is a suggestion that application of a pressure immobilization bandage may worsen the envenomation. We include our recommended treatment for the Irukandji syndrome.

Pressure immobilisation bandages in first-aid treatment of jellyfish envenomation: current recommendations reconsidered.

OBJECTIVE: To evaluate whether applying pressure equivalent to that of pressure immobilisation bandages (PIB) causes release of additional venom from discharged jellyfish nematocysts. DESIGN: In-vitro experiment--the venom beads released from electrically activated Chiropsalmus sp. nematocysts were viewed under direct microscopy before and after applying 40 mmHg pressure (replicating the pressure of PIB); and saline washings of discharged nematocysts before and after applying pressure were tested for toxicity (time to ventricular standstill after injecting into live prawns). RESULTS: Applying 40 mmHg pressure caused the venom beads to visibly increase in size, consistent with pressure expressing further venom from the discharged nematocysts. First washings of the nematocyst shafts before compression produced ventricular standstill in prawns within 60 seconds (n=3); second washings did not produce standstill during 540 seconds of observation (n=3); and washings after applying 40 mmHg pressure showed a return of toxicity, with ventricular standstill in all prawns within 180 seconds (n=3). CONCLUSION: Discharged nematocysts are by no means empty and harmless. Applying pressure results in further release of nematocyst venom. The currently recommended practice of applying PIB in the initial treatment of patients stung by a jellyfish may exacerbate the envenomation, and thus should not be recommended.

A year's experience of Irukandji envenomation in far north Queensland.

Envenomation by the Irukandji jellyfish (Carukia barnesi) can result in an array of systemic symptoms known as Irukandji syndrome. In 1996, 62 people presented to Cairns emergency departments with Irukandji envenomation: 57 developed systemic symptoms, and 38 required parenteral narcotics. All patients were discharged home within 24.5 hours, except for two who required high-dependence care for pulmonary oedema. Patients were more likely to be stung on hotter days, with lower-than-average rainfall in the past seven days, and with winds from the north, but less-than-average wind speed. We offer a protocol for treating patients with Irukandji envenomation.

Metabolism of bioreductive antitumor compounds by purified rat and human DT-diaphorases.

The metabolisms of two standard electron acceptors and a series of bioreductive antitumor compounds by purified rat and human DT-diaphorases (DTD) were compared. DTD was purified from rat liver cytosol and from Escherichia coli in which rat liver or human lung tumor DTD complementary DNA was expressed. Km and kcat values for menadione and 2,6-dichlorophenolindophenol reduction were similar for the three enzyme preparations except that rat E. coli DTD had 2-3-fold higher kcat values for both menadione and 2,6-dichlorophenolindophenol and a 2-3-fold higher Km for menadione than either rat liver or human E. coli DTD. Reduction of the antitumor compounds was 1.9-4.9 times faster with rat E. coli DTD than with human E. coli DTD. The antitumor compounds were reduced in the following order by rat E. coli DTD: 2,5-dimethyl-3,6-diaziridinyl-1,4-benzoquinone > streptonigrin > mitomycin A > diaziquone > mitomycin C (MC) > 5-(aziridin-1-yl)-2,4-dinitrobenzamide. The order was the same for human E. coli DTD with one exception; diaziquone was reduced slightly faster than mitomycin A. Metabolism of doxorubicin could not be detected using rat or human E. coli DTD. MC-induced DNA cross-linking was also more efficient using rat E. coli DTD relative to human E. coli DTD. Metabolism of MC by rat and human E. coli DTD was also compared under aerobic and hypoxic conditions. Rates of reduction of MC and metabolite formation were similar under aerobic and hypoxic conditions, and the toxicity of MC to DTD-rich HT-29 cells was also similar in aerobic and hypoxic conditions. In contrast, the toxicity of MC to DTD-deficient BE cells was potentiated markedly under hypoxia. These data show that although small catalytic differences between rat and human E. coli DTD can be observed, compounds such as 2,5-dimethyl-3,6-diaziridinyl-1,4-benzoquinone and streptonigrin are still excellent substrates for the human enzyme and may be useful in the therapy of tumors high in DTD activity. In addition, metabolism of MC by rat and human E. coli DTD was similar in aerobic and hypoxic conditions; in agreement with these data, cytotoxicity of MC to a DTD-rich cell line was oxygen independent. Increased MC cytotoxicity under hypoxia appears to be mediated by enzymes other than DTD.

Interactions between hyperthermia and irradiation in two human lymphoblastic leukemia cell lines in vitro.

Thermal radiosensitization was studied in two human T-cell acute lymphoblastic leukemia cell lines (JM and MOLT3) with regard to heat-irradiation sequence and heating duration. In MOLT3 thermal radiosensitization was maximal when 43.5 degrees C hyperthermia immediately preceded or followed irradiation; at 41.5 degrees C, radiosensitization was maximal with hyperthermia immediately before or up to 3 h after irradiation. In JM, enhancement of radiation killing was unexpectedly maximal when 41.5 or 43.5 degrees C hyperthermia preceded irradiation by 2 to 4 h. Thermal radiosensitization increased exponentially with increasing duration of heating at 41.5 degrees C for at least 3 h in MOLT3. In contrast, in JM, radiosensitization increased exponentially for 1.6 h but additional heating (up to 3 h net heating) had no appreciable further effect on radiation killing. For JM, repair of single and double stranded DNA breaks was investigated using alkaline and neutral elution techniques to determine whether the unusual results regarding heat-irradiation sequencing were related to effects of heat on repair of DNA damage. These studies were unable to detect significant differences in repair of single or double stranded DNA breaks between unheated control cells and cells heated at 41.5 degrees C for 1 h ending 4 h before irradiation. The direct cytotoxicity of hyperthermia was also studied in both cell lines.

Enhancement of misonidazole chemopotentiation by mild hyperthermia (41 degrees C) in vitro and selective enhancement in vivo.

Experiments were designed to test the hypothesis that mild heat treatment would selectively increase misonidazole (MISO) chemopotentiation of CCNU toxicity in hypoxic versus aerobic cells in vitro and in tumours in vivo via an augmentation of nitroreduction. EMT-6 cells were exposed to CCNU +/- 1.0 mM MISO under aerobic or hypoxic conditions for 4 h either at a constant 37 degrees C or at 41 degrees C for the first hour followed by 37 degrees C for the remaining 3 h. Chemopotentiation was not observed under aerobic conditions and heat treatment did not modify CCNU toxicity. Co-incubation with MISO and CCNU under hypoxic conditions resulted in enhanced toxicity (i.e. chemopotentiation) with either incubation protocol; however, the magnitude of the enhancement was significantly larger (P less than 0.025) when 41 degrees C incubation was included. Systemic heat treatment produced a similar enhancement of chemopotentiation in KHT tumours in C3H/HeN mice treated with MISO (0.5 mg g-1) and whole body hyperthermia (41 degrees C, 1 h) prior to administration of CCNU (15 mg kg-1). Heating had no effect on CCNU response but doubled the median growth delay produced by the CCNU-MISO combination. Heat treatment did not enhance myelosuppression of the combination. Both the in vitro and in vivo data indicate that mild hyperthermia can selectively enhance the magnitude of MISO chemopotentiation.

Diet and 20-year mortality from coronary heart disease. The Ireland-Boston Diet-Heart Study.

In a prospective epidemiologic study of 1001 middle-aged men, we examined the relation between dietary information collected approximately 20 years ago and subsequent mortality from coronary heart disease. The men were initially enrolled in three cohorts: one of men born and living in Ireland, another of those born in Ireland who had emigrated to Boston, and the third of those born in the Boston area of Irish immigrants. There were no differences in mortality from coronary heart disease among the three cohorts. In within-population analyses, those who died of coronary heart disease had higher Keys (P = 0.06) and modified Hegsted (P = 0.02) dietary scores than did those who did not (a high score indicates a high intake of saturated fatty acids and cholesterol and a relatively low intake of polyunsaturated fatty acids). These associations were significant (P = 0.03 for the Keys and P = 0.04 for the modified Hegsted scores) after adjustment for other risk factors for coronary heart disease. Fiber intake (P = 0.04) and a vegetable-foods score, which rose with increased intake of fiber, vegetable protein, and starch (P = 0.02), were lower among those who died from coronary heart disease, though not significantly so after adjustment for other risk factors. A higher Keys score carried an increased risk of coronary heart disease (relative risk, 1.60), and a higher fiber intake carried a decreased risk (relative risk, 0.57). Overall, these results tend to support the hypothesis that diet is related, albeit weakly, to the development of coronary heart disease.

Changes in GSR and heart rate during listening to tones, words, and nonsense syllables.

In order to compare the habituation of orienting responses to tones, words, and nonsense syllables, GSR and heart rate were recorded following mass (habituation) and discrete presentations of the stimuli. Each of 36 10-yr.-old boys and 36 male undergraduates listened to two presentations of a tone (word and nonsense syllable in a random order) under discrete condition in contrast to 40 presentations under mass condition. Immediately following 2 or 40 presentations, habituation of orienting response was measured while five instances of the stimulus were slowly presented. Results indicated (i) habituation of GSR but not of heart rate, (ii) nonsense syllables evoked the strongest GSRs and heart-rate changes among the three stimuli, and (iii) children showed stronger reactions than the adults in some measure of GSR and heart rate. These results were discussed in terms of the theory of Sokolov.