Nutritional Changes and Micronutrient Supply in Patients with Phenylketonuria Under Therapy with Tetrahydrobiopterin (BH(4)).

BACKGROUND: Since 2008 patients with BH(4)-sensitive phenylketonuria can be treated with sapropterin dihydrochloride (Kuvan®) in addition to the classic phenylalanine (Phe) restricted diet. The aim of this study was to evaluate the nutritional changes and micronutrient supply in patients with phenylketonuria (PKU) under therapy with tetrahydrobiopterin (BH(4)). SUBJECTS AND METHODS: 19 children with PKU (4-18 years) and potential BH(4)-sensitivity were included, 14 completed the study protocol. Dried blood Phe concentrations as well as detailed dietary records were obtained throughout the study at preassigned study days. RESULTS: Eight patients could increase their Phe tolerance from 629 ± 476 mg to 2131 ± 1084 mg (P = 0.006) under BH(4) while maintaining good metabolic control (Phe concentration in dried blood 283 ± 145 µM vs. 304 ± 136 µM, P = 1.0), therefore proving to be BH(4)-sensitive. They decreased their consumption of special low protein products and fruit while increasing their consumption of high protein foods such as processed meat, milk and dairy products. Intake of vitamin D (P = 0.016), iron (P = 0.002), calcium (P = 0.017), iodine (P = 0.005) and zinc (P = 0.046) significantly declined during BH(4) treatment while no differences in energy and macronutrient supply occurred. CONCLUSION: BH(4)-sensitive patients showed good metabolic control under markedly increased Phe consumption. However, the insufficient supply of some micronutrients needs consideration. Long-term multicenter settings with higher sample sizes are necessary to investigate the changes of nutrient intake under BH(4) therapy to further evaluate potential risks of malnutrition. Supplementation may become necessary.

Photoperiodic variations of the polysialylated form of neural cell adhesion molecule within the hypothalamus and related reproductive output in the ewe.

Cellular mechanisms induced by melatonin to synchronise seasonal reproduction in several species, including sheep, remain unclear. We sought to evaluate the scale and physiological significance of neural plasticity in order to explain the delay between the change of duration of melatonin secretion and the change of reproductive status following a transition from long days (LD, 16 h light/24 h) to short days (SD, 8 h light/24 h) and from SD to LD. Using Western blots in ovariectomised oestradiol-replaced ewes, we evaluated the content of the polysialylated form of neural cell adhesion molecule (PSA-NCAM), a plasticity marker, in the hypothalamus. From day 15 following a transition to SD, most hypothalamic areas showed a decrease of PSA-NCAM level that was particularly significant in the preoptic area (POA). Following a transition to LD, PSA-NCAM content increased at day 15 in most regions except in the premammillary hypothalamic area (PMH) in which a significant decrease was noted. The functional importance of PSA-NCAM variations for seasonal reproduction was assessed for the PMH and POA. PSA-NCAM was degraded by stereotaxic injections of endoneuraminidase N and luteinising hormone (LH) secretion was recorded in treated and control ewes. Degradation of PSA-NCAM in the PMH in SD-treated ewes failed to produce a significant effect on LH secretion, whereas a similar treatment in the POA before a transition to SD delayed activation of the gonadotroph axis in two-thirds of the ewes. Our results suggest that the photoperiod controls variations of the hypothalamic content of a plasticity marker and that these might be important for the regulation of seasonal reproduction, particularly in the POA.

Impact of atorvastatin and omega-3 ethyl esters 90 on plasma plant sterol concentrations and cholesterol synthesis in type 2 diabetes: a randomised placebo controlled factorial trial.

OBJECTIVE: To determine the effects of statin treatment and omega-3 polyunsaturated fatty acid supplementation on plasma plant sterol concentrations and cholesterol synthesis in patients with type 2 diabetes. METHODS: Plant sterol concentrations and lanosterol (a marker of cholesterol synthesis) were measured using a high sensitivity assay to assess the effect of double-blind daily treatment for 4 months with atorvastatin 20mg or placebo and, in a 2 × 2 factorial design, omega-3 ethyl esters 90 2g or placebo. RESULTS: 658 patients were included in a per protocol analysis. The 4 treatment groups had similar mean [SD] age (63.5 years [11.7]), HbA(1c) (6.9% [1.1]) and diabetes duration (median 4 years [inter-quartile range 2, 8]). Atorvastatin treatment alone reduced low density lipoprotein (LDL) cholesterol by 1.4 mmol/l (44%, p<0.001), triglycerides by 0.3 mmol/l (20%, p<0.0001) and lanosterol by 0.36 µmol/l (72%, p<0.001). There was no significant placebo adjusted change in median [95% confidence intervals] total plant sterol concentrations (-0.77 µmol/l [inter-quartile range -2.13, 0.59]), although they were increased significantly with omega-3-acid EE90 treatment (3.23 µmol/l [1.28, 5.17]). There was a 27% smaller reduction in LDL cholesterol with atorvastatin treatment in low cholesterol synthesisers with high absorption, defined by changes at or above the median lanosterol and campesterol levels, respectively, compared with the obverse group (difference 0.42 mmol/l [0.21, 0.62]). CONCLUSION: Treatment with atorvastatin in type 2 diabetes did not change median total plasma plant sterol concentrations, but LDL cholesterol was reduced most efficaciously in high cholesterol synthesisers with low intestinal cholesterol absorption. CLINICAL TRIAL REGISTRATION INFORMATION: Current controlled trials number ISRCTN: 76737502 (http://isrctn.org).

Plant sterols from rapeseed and tall oils: effects on lipids, fat-soluble vitamins and plant sterol concentrations.

BACKGROUND AND AIMS: Data comparing the impact of different sources of plant sterols on CVD risk factors and antioxidant levels is scarce. We evaluated the effects of plant sterols from rapeseed and tall oils on serum lipids, lipoproteins, fat-soluble vitamins and plant sterol concentrations. METHODS AND RESULTS: This was a double-blinded, randomized, crossover trial in which 59 hypercholesterolemic subjects consumed 25 g/day of margarine for 4 weeks separated by 1 week washout periods. The two experimental margarines provided 2g/day of plant sterols from rapeseed or tall oil. The control margarine had no added plant sterols. The control margarine reduced LDL cholesterol by 4.5% (95% CI 1.4, 7.6%). The tall and rapeseed sterol margarines additionally reduced LDL cholesterol by 9.0% (95% CI 5.5, 12.4%) and 8.2% (95% CI 5.2, 11.4%) and apolipoprotein B by 5.3% (95% CI 1.0, 9.6%) and 6.9% (95% CI 3.6, 10.2%), respectively. Lipid-adjusted beta-carotene concentrations were reduced by both sterol margarines (P<0.017). alpha-Tocopherol concentrations were reduced by the tall sterol compared to the rapeseed sterol margarine (P=0.001). Campesterol concentrations increased more markedly with the rapeseed sterol versus tall sterol margarine (P<0.001). The rapeseed sterol margarine increased while the tall sterol margarine decreased brassicasterol concentrations (P<0.001). CONCLUSIONS: Plant sterols from tall and rapeseed oils reduce atherogenic lipids and lipoproteins similarly. The rapeseed sterol margarine may have more favorable effects on serum alpha-tocopherol concentrations.

The influence of garlic (Allium sativum) extract on interleukin 1alpha-induced expression of endothelial intercellular adhesion molecule-1 and vascular cell adhesion molecule-1.

Inflammation plays an important role in both the initiation of atherosclerosis and development of atherothrombotic events. The adherence of leukocytes/monocytes to the endothelium is an early event in atherogenesis. Phytotherapeutica as garlic and garlic extracts were shown to have beneficial modulating effects in patients with atherosclerotic disease. The aim of this study was to evaluate in vitro the influence of water-soluble garlic (Allium sativum) extract on the cytokine-induced expression of endothelial leukocyte adhesion molecules such as intercellular adhesion molecule-1 (ICAM-1, CD54) and vascular cell adhesion molecule-1 (VCAM-1, CD106). Cytokine-induced expression of cellular adhesion molecules was measured on primary human coronary artery endothelial cell (HCAEC) cultures. HCAEC were cultured in microvascular endothelial cell growth medium and preincubated with garlic extract at various concentrations (0.25-4.0 mg/ml), after which human interleukin-1alpha (IL-1alpha, 10 ng/ml) was added for 1 day. Fluorescein isothiocyanate (FITC)-labeled anti-ICAM-1 and FITC-labeled anti-VCAM-1 were used to analyze the IL-1alpha-induced expression of ICAM-1 and VCAM-1 by flow cytometry. Incubation of HCAEC with garlic extract significantly decreased ICAM-1 and VCAM-1 expression induced by IL-1alpha. In addition, we examined the effects of garlic extract on the adhesion of monocytes to endothelial cells, using the monocytic U937 cell line. The presence of garlic extract significantly inhibited the adhesion of monocytes to IL-1alpha-stimulated endothelial cells. These results indicate that garlic extract modulates the expression of ICAM-1 and VCAM-1, thus potentially contributing to the beneficial effects traditionally attributed to garlic.

[The "incorrect" laboratory result. II: Common misinterpretations of laboratory results]. / Der "fehlerhafte" Laborbefund. Teil 2: Häufige Ursachen von Fehlinterpretationen labormedizinischer Befunde.

In the second part of our review the most frequent misinterpretations of laboratory results in the daily clinical practise are discussed. Special attention has been given to frequent misinterpretations in the analysis of electrolytes, enzymes and hormones in plasma/serum (pseudohyperkalemia, macroenzymes, macroprolactinemia). Misinterpretations of the testing of blood gases, serum glucose, lipid concentrations, and calcium are described in greater detail. In addition, potential errors in the urinanalysis and the importance of adequate sampling of blood specimens for coagulation testing are described. The hematological results can be misinterpreted in the presence of EDTA-induced pseudothrombocytenia and of irregular immunoglobulines. Immunological methods themselves can lead to misinterpretations of the laboratory result, e. g. caused by the high dose hook effect and interferences in the presence of rheumatoid factor or HAMA. Finally clinical relevant errors in the therapeutic drug monitoring are discussed which are associated with the limited specificity of the antibodies in the commonly used immunological tests.

Estradiol increases multiunit electrical activity in the A15 area of ewes exposed to inhibitory photoperiods.

Seasonal anestrus in ewes results from an increase in response to the negative feedback action of estradiol (E(2)). This increase in the inhibitory effects of E(2) is controlled by photoperiod and appears to be mediated, in part, by dopaminergic neurons in the retrochiasmatic area of the hypothalamus (A15 group). This study was designed to test the hypothesis that E(2) increases multiunit electrical activity (MUA) in the A15 during inhibitory long days. MUA was monitored in the retrochiasmatic area of 14 ovariectomized ewes from 4 h before to 24 h after insertion of an E(2)-containing implant subcutaneously. In six of these ewes, MUA activity was also monitored before and after insertion of blank implants. Three of the 14 ewes were excluded from analysis because E(2) failed to inhibit LH. When MUA was recorded within the A15, E(2) produced a gradual increase in MUA that was sustained for 24 h. Blank implants failed to increase MUA in the A15 area, and E(2) did not alter MUA if recording electrodes were outside the A15. These data demonstrate that E(2) increases MUA in the A15 region of ewes and are consistent with the hypothesis that these neurons mediate E(2) negative feedback during long photoperiods.

Impact of hyperthermic preconditioning on postischemic hepatic microcirculatory disturbances in an isolated perfusion model of the rat liver.

Sublethal hyperthermia and the following recovery from this heat exposure, referred to as hyperthermic preconditioning, elicits a transient state of tolerance to oxidative insults through an intracellular protective response: stress response. The impact of hyperthermic preconditioning on hepatic microcirculatory disturbance, which is one of the determinants of ischemia/reperfusion-induced injury of the liver, was investigated by using intravital fluorescence microscopy. Thirty minutes of ischemia and a subsequent 120 minutes of reperfusion was induced in an in situ isolated perfusion model of Sprague-Dawley rats. Heat stress was given by whole-body hyperthermia, and a subsequent recovery was allowed for 18 or 48 hours, respectively. Postischemic decrease in sinusoidal perfusion rate and sinusoidal diameter, leukocyte stagnation in sinusoids, and leukocyte adhesion in postsinusoidal venules were significantly attenuated in both hyperthermia-pretreated groups. A recovery of bile production, a reduction of liver enzyme release, and an attenuation of tissue edema and histological damage were also observed. A marked expression of heat shock protein (HSP) 70 and heme oxygenase (HO-1)/HSP32 was correlatively observed in the liver tissue coincident with the induction of these protective effects. Hyperthermic preconditioning provides a continuous long-term and constant inhibitory effect (up to 48 hours after heat exposure) on postischemic injury of the liver through the attenuation of microcirculatory disturbances. These beneficial effects might be associated with a concomitant increase in HSP70 and HO-1/HSP32 expression.

The zinc-finger protein slug causes desmosome dissociation, an initial and necessary step for growth factor-induced epithelial-mesenchymal transition.

Epithelial-mesenchymal transition (EMT) is an essential morphogenetic process during embryonic development. It can be induced in vitro by hepatocyte growth factor/scatter factor (HGF/SF), or by FGF-1 in our NBT-II cell model for EMT. We tested for a central role in EMT of a zinc-finger protein called Slug. Slug mRNA and protein levels were increased transiently in FGF-1-treated NBT-II cells. Transient or stable transfection of Slug cDNA in NBT-II cells resulted in a striking disappearance of the desmosomal markers desmoplakin and desmoglein from cell-cell contact areas, mimicking the initial steps of FGF-1 or HGF/SF- induced EMT. Stable transfectant cells expressed Slug protein and were less epithelial, with increased cell spreading and cell-cell separation in subconfluent cultures. Interestingly, NBT-II cells transfected with antisense Slug cDNA were able to resist EMT induction by FGF-1 or even HGF/SF. This antisense effect was suppressed by retransfection with Slug sense cDNA. Our results indicate that Slug induces the first phase of growth factor-induced EMT, including desmosome dissociation, cell spreading, and initiation of cell separation. Moreover, the antisense inhibition experiments suggest that Slug is also necessary for EMT.

Estradiol acts locally within the retrochiasmatic area to inhibit pulsatile luteinizing-hormone release in the female sheep during anestrus.

In the present study we have identified a site of action of estradiol in the inhibition of LH secretion during anestrus in the ewe. In the first experiment, we studied six sites: the medial preoptic area, the lateral preoptic area, the ventromedial hypothalamus, the ventrolateral hypothalamus, the retrochiasmatic area (RCh), and the periventricular posterior hypothalamus. We compared the changes in parameters of pulsatile LH secretion (interpulse interval, mean nadir, mean amplitude, and mean area under curve) during three 6-h sampling periods: before and 30-36 h and 9 days after intracerebral implantation of crystalline estradiol. Animals that received estradiol in the RCh (n = 5) showed a significantly greater increase in both the intervals between pulses of LH (up 116%, p < 0.03) and the area under the curve (up 180%, p < 0.01) than any of the other groups of 7 animals. In the second experiment, implantation of estradiol in the RCh (n = 6) induced an increase in the intervals between pulses of LH (p < 0.03), whereas receiving an empty implant (n = 6) had no effect, showing that estradiol specifically induced increases in the intervals between pulses. Thus, estradiol appears to act in the RCh where the dopaminergic A15 nucleus, known to inhibit pulsatile LH release, is located.

Initiation of the oestradiol-induced inhibition of pulsatile LH secretion in ewes under long days: comparison of peripheral versus central treatment and neurochemical correlates.

In the ewe, the inhibition of pulsatile LH secretion by oestradiol during long days depends on dopaminergic activity and could involve amino acid transmitters. In the first experiment of the present study we observed the changes in LH secretion in ovariectomised ewes under long days immediately after subcutaneous implantation of oestradiol (peripheral treatment). In the second experiment, in order to identify the site of action of oestradiol, we observed the LH changes following intracerebral infusion of oestradiol through a microdialysis membrane (central treatment) within the preoptic area, the mediobasal hypothalamus (MBH) or the retrochiasmatic area (RCh) and measured amino acids and catecholaminergic transmitters and metabolites within the dialysates. With peripheral treatment, the amplitude, the nadir and the area under the LH pulse curve decreased within 4 to 8 h of the insertion of a subcutaneous oestradiol implant. After 18 h, the amplitude and the area under the pulses increased, as well as the intervals between pulses (from 49.9 + 1.4 min to 75.6 +/- 5.9 min). With central oestradiol treatment. LH changes were similar whatever the site of oestradiol infusion, suggesting either multiple sites of action or diffusion between structures. Twenty hours after the beginning of intracerebral oestradiol treatment, the amplitude and the area under the pulses increased, as did the interval between LH pulses (from 49.5 +/- 4.1 min to 73.2 +/- 14.2 min). Comparison of peripheral with central oestradiol treatment suggested that the long-lasting decrease in the nadir, as well as the transitory decrease in the amplitude and area, before 18 h in experiment 1 are reflections of hypophysial effects. In contrast, the increases in amplitude and area under the LH pulse curve seen 18-20 h after oestradiol in the two experiments could be due to the higher amplitude of LHRH pulses, as a result of an early stimulatory effect of oestradiol. After central oestradiol infusion, there was a decline in the concentration in the dialysate of two metabolites of dopamine, 3,4-dihydroxyphenylacetic acid and homovanillic acid in the RCh, suggesting an early inhibition of monoamine oxidase by the steroid. During the inhibition of LH pulsatility the concentration of gamma-aminobutyric acid in the dialysate from the RCh and the MBH increased, suggesting the participation of this transmitter in the changes induced by oestradiol under long days.

Photoperiodic modulation of monoamines and amino-acids involved in the control of prolactin and LH secretion in the ewe: evidence for a regulation of tyrosine hydroxylase activity.

Several neurotransmitters are implicated in the photoperiodic regulation of prolactin and luteinising hormone (LH) secretion in the ewe. This work investigated whether catecholamines, gamma-amino butyric acid (GABA), excitatory amino acids and serotonin diencephalic contents are affected by photoperiod and how such changes relate to the seasonal effects of photoperiod on LH and prolactin secretions. Moreover, to determine whether photoperiod can influence catecholamine biosynthesis, the activity of its rate limiting enzyme, tyrosine hydroxylase (TH) was also investigated. TH activity and the tissue content of the monoamines and their metabolites were measured in stalk-median eminence (SME), preoptic area (POA) and the mediobasal, mediodorsal and laterobasal aspects of the hypothalamus. Investigation of excitatory amino acids and GABA was limited to the POA and the SME. Ovariectomized ewes were initially maintained in long days (LD) for 70 days. Thereafter half the ewes remained exposed to long days and the other half were transferred onto short days (SD) for 63 to 66 days to induce a stimulation of LH secretion and an inhibition of prolactin secretion. In each photoperiodic regime, half the ewes were treated with a subcutaneous oestradiol implant (+E) and half were not (-E). As expected, short days induced a decrease in prolactin and an increase in pulsatile LH secretion. These neuroendocrine changes were associated with a decrease in the TH activity of the SME in both oestradiol treated and non treated animals (146.5 +/- 24.1, 167.6 +/- 26.5 U TH/g of tissue in LD-E and LD+E vs 83.5 +/- 12.4 and 95.0 +/- 30.2 U TH/g of tissue in SD-E and SD+E animals; P < or = 0.01). A similar and parallel short day-induced decrease was observed in the tissue content of dopamine and its metabolite, 3,4-dihydroxy-phenylacetic acid (SD level were 55% of LD levels, P < 0.05). In POA, a short day-induced decrease in dopamine (18%; P < or = 0.05) and GABA (16.4%; P < or = 0.05) content and an oestradiol-induced decrease in aspartate (15.6%; P < or = 0.05) content were found. This study provides the first report of a photoperiodic control of the synthesis activity of catecholaminergic neurones of the SME in the ewe. The photoperiod-induced changes in dopaminergic activity at the level of the SME were associated with changes in LH and prolactin secretion indicating that TH activity of dopaminergic neurones of the SME could be a critical component of the photoperiodic regulation of LH and/or prolactin secretion. In particular, this finding is in agreement with the hypothesis that photoperiod can control a dopaminergic pathway inhibitory of LH secretion and which ends in the median eminence.

Relative resistance of the hamster to aortic atherosclerosis in spite of prolonged vitamin E deficiency and dietary hypercholesterolemia. Putative effect of increased HDL?

UNLABELLED: Male golden hamsters were rendered hypercholesterolemic by feeding diets enriched with cholesterol and fat. In the first series of experiments, 5% butter and 1% cholesterol were added to a chow diet and plasma cholesterol levels were maintained at 350-390 mg/dl over the entire experimental period. Groups of hamsters and their age controls consuming the chow diet, were killed after 7, 15 and 20 months when the aorta was examined for atherosclerosis by determination of cholesterol mass. In the controls, aortic total cholesterol (TC) increased with age by 28% and esterified cholesterol increased to 11% of TC. In the hypercholesterolemic animals aortic TC was only 28% higher than in the controls and cholesteryl ester was also 11.5% of TC. In the second series, one group of hamsters were fed a semi-purified diet deficient in vitamin E, containing 1% cholesterol and 10% lard; a second group received the same diet, but supplemented with vitamin E. Controls consumed local chow. After 7 months on the vitamin E deficient diet plasma alpha-tocopherol was 0.05 mg/l, in those supplemented with vitamin E it was 20 mg/l, while in the controls it was 3.3 mg/l. Plasma thiobarbituric acid reactive substances (TBARS) were higher in the vitamin E deficient group and there was a greater propensity of lipoproteins (d < 1.063 g/ml) to peroxidation in vitro than in the vitamin E supplemented group. Plasma cholesterol was 366 mg/dl in the vitamin E deficient, 336 mg/dl in the vitamin E supplemented group, and 64 mg/dl in controls. Aortic cholesterol was 79.1 in vitamin E supplemented and 84.4 micrograms/10 mg dry weight in vitamin E deficient hamsters. In both series of experiments, HDL amounted to 36-41% of plasma TC in the hypercholesterolemic animals and 59-62% in the controls. IN CONCLUSION: the hamster appears to be quite resistant to atherosclerosis in face of sustained hypercholesterolemia, even in the presence of increased peroxidative stress caused by vitamin E deficiency. This relative resistance could be related to commensurate increase in plasma HDL which was observed in both series of experiments. Since vitamin E deficiency did not enhance aortic cholesteryl ester deposition, the protective effect of HDL seems to be related to its role in reverse cholesterol transport, rather than in prevention of peroxidation.

Plasmalogen phospholipids in plasma lipoproteins of normolipidemic donors and patients with hypercholesterolemia treated by LDL apheresis.

Recent evidence indicates that plasmalogen phospholipids are particularly sensitive to oxidation and may possess antioxidative properties. Approximately 4.4%-5.5% of phosphatidylcholine (PC), and 53%-60% of phosphatidylethanolamine (PE) consisted of the plasmalogen phospholipids, plasmenylcholine and plasmenylethanolamine, respectively, in whole plasma, low density lipoprotein (LDL) and high density lipoprotein (HDL) of 11 normolipidemic donors. Of total plasmalogen phospholipids in plasma, slightly more was associated with LDL particles (about 42%) than with HDL (36%). Plasmalogen phospholipid levels were analyzed in 12 patients with familial hypercholesterolemia (FH) regularly treated by LDL apheresis, of whom 6 were supplemented with vitamin E (alpha tocopherol, 400 IU/day), the remaining 6 not receiving the antioxidant. Before apheresis (pre), total plasmalogen phospholipid levels in plasma and LDL (expressed as mumol/mmol cholesterol of compartment) decreased as follows: patients receiving vitamin E > normolipidemia > patients not receiving vitamin E. In both hypercholesterolemic groups, the contents of plasmalogen phospholipids in whole plasma and LDL were 3-5-fold higher than those of vitamin E. Directly after apheresis (post), plasmalogen phospholipid levels in plasma were raised by about 50% in the two hypercholesterolemic groups, mostly due to increases in plasmenylethanolamine levels. Two days after apheresis (48 h post), plasmalogen contents were still elevated in plasma and red blood cell membranes of patients receiving vitamin E, while they had already reached pre-apheresis values in those not supplemented with alpha tocopherol. Molecular species of plasma diacyl phospholipids containing polyunsaturated fatty acids were elevated at pre in patients receiving vitamin E as compared to patients without supplementation. At 48 h post, LDL apheresis induced an increase in these molecular species only in patients receiving vitamin E. In conclusion, the contents of plasmalogen phospholipids in plasma lipoproteins are at least three times higher than those of vitamin E. LDL apheresis raises the level of plasmalogen phospholipids in plasma, the increase persisting longer in patients supplemented with vitamin E. Supplementation with vitamin E appears to protect plasmalogen phospholipids in plasma lipoproteins against oxidative degradation.

Impact of vitamin E supplement in standard laboratory animal diet on microvascular manifestation of ischemia/reperfusion injury.

Aimed at improving animal fertility and health, diets for farm and laboratory animals have over the last few years been supplemented with increasing amounts of the antioxidant vitamin E. We now demonstrate by intravital microscopy that feeding hamsters with a vitamin E-supplemented "standard" rodent diet (60 ppm vitamin E) significantly reduces the microvascular manifestations of ischemia/reperfusion injury when compared to animals fed a nonsupplemented diet. Postischemic leukocyte adhesion to venular endothelium was reduced from 770 +/- 204 cells/mm2 at 24 h after reperfusion in control animals on the nonsupplemented diet to 403 +/- 105 cells/mm2 in animals on the "standard" rodent diet (means +/- SD, n = 7 animals per group, p < 0.01). Animals on the nonsupplemented diet showed a dramatic loss of capillary perfusion density until 7 days after reperfusion (to 21 +/- 13% of preischemic baseline values), whereas this loss was significantly attenuated (to 71 +/- 12% of preischemic values, p < 0.01) in animals on the "standard" rodent diet. No difference in the extent of reperfusion injury was seen between animals on the "standard" rodent diet and animals on diets with substantially higher vitamin E supplements (300 ppm-30,000 ppm). Besides underscoring the benefit of vitamin E in reducing the extent of ischemia/reperfusion injury, this study raises the concern that vitamin E supplements in "standard" laboratory animal diets may have a far-reaching impact on biomedical research by jeopardizing established animal models of disease.

Effect of hypothalamic infusion of a dopamine D1 receptor antagonist on prolactin secretion in the ewe.

In this study we investigated whether dopamine D1 receptors in the hypothalamus are involved in the control of prolactin secretion in ovariectomised, oestradiol implanted ewes. The D1 antagonist SCH23390 or vehicle was infused into either the preoptic area (POA) or the ventromedial hypothalamus (VMH). During infusion into the VMH, prolactin concentrations declined significantly and did not return to control values until more than 60 min after the infusions had stopped. In contrast, infusion into the POA had no significant effect. These results are in accord with the hypothesis that dopaminergic pathways within the hypothalamus stimulate prolactin secretion via dopamine D1 receptors in the VMH.

Dopaminergic control of LH secretion by the A15 nucleus in anoestrous ewes.

Annual variations in the secretion of LH are responsible for seasonal changes in ovulatory activity in ewes. This hormonal pattern reflects an increase in the intensity of the negative feedback exerted by oestradiol under long days. Neuropharmacological studies have shown that this inhibition of LH secretion involves activation of catecholaminergic systems from preoptic and mediobasal hypothalamus (MBH) by oestradiol during anoestrus, and that 5-hydroxytryptamine inputs may also play a role. Within the MBH, the most important structures appear to be the retrochiasmatic region of the hypothalamus, which contains the A15 dopaminergic nucleus, and the median eminence, which contains the axon terminals of the GnRH cells controlling the pulsatile release of LH. In ovariectomized ewes in which oestradiol tonically inhibits LH secretion during the anoestrous season, LH pulse frequency is increased when the cells of the A15 nucleus are destroyed. The median eminence and other mediobasal structures contain more catecholamines and their metabolites under long days than under short days. Microdialysis of the A15 nucleus in vivo during long days revealed increased catecholaminergic activity under oestradiol treatment due to stimulation of tyrosine hydroxylase, the rate-limiting enzyme in the pathway of catecholaminergic synthesis. Tyrosine hydroxylase activity within the median eminence is increased under the various photoperiodic regimens that inhibit LH secretion. Neurochemical changes in the A15 nucleus and median eminence, in response to photoperiodic or oestradiol treatments, suggest a functional relationship which acts at the level of the GnRH axon terminals.